From a8551243ea149fdf621d34bcef3bd447a07dfdfc Mon Sep 17 00:00:00 2001
From: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
Date: Sat, 20 Jun 2026 00:54:58 -0400
Subject: [PATCH 1/9] Add safe_eval Function

Signed-off-by: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
---
 monai/utils/__init__.py       |  1 +
 monai/utils/safe_eval.py      | 75 +++++++++++++++++++++++++++++++++++
 tests/utils/test_safe_eval.py | 55 +++++++++++++++++++++++++
 3 files changed, 131 insertions(+)
 create mode 100644 monai/utils/safe_eval.py
 create mode 100644 tests/utils/test_safe_eval.py

diff --git a/monai/utils/__init__.py b/monai/utils/__init__.py
index 3efc9b5e7f..d0f4eb40ce 100644
--- a/monai/utils/__init__.py
+++ b/monai/utils/__init__.py
@@ -137,6 +137,7 @@
     torch_profiler_time_cpu_gpu,
     torch_profiler_time_end_to_end,
 )
+from .safe_eval import SAFE_TYPES, safe_eval
 from .state_cacher import StateCacher
 from .tf32 import detect_default_tf32, has_ampere_or_later
 from .type_conversion import (
diff --git a/monai/utils/safe_eval.py b/monai/utils/safe_eval.py
new file mode 100644
index 0000000000..9c5293e229
--- /dev/null
+++ b/monai/utils/safe_eval.py
@@ -0,0 +1,75 @@
+# Copyright (c) MONAI Consortium
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#     http://www.apache.org/licenses/LICENSE-2.0
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import ast
+from typing import Any, Mapping, Sequence
+
+__all__ = ["SAFE_TYPES", "safe_eval"]
+
+# default set of safe AST node types
+SAFE_TYPES = (
+    ast.Expression,
+    ast.Name,
+    ast.Load,
+    ast.Constant,
+    ast.BinOp,
+    ast.UnaryOp,
+    ast.Add,
+    ast.Sub,
+    ast.Mult,
+    ast.Div,
+    ast.FloorDiv,
+    ast.Pow,
+    ast.Mod,
+    ast.USub,
+    ast.UAdd,
+)
+
+
+def safe_eval(
+    expr: str,
+    globals: Mapping[str, Any] | None = None,
+    locals: Mapping[str, object] | None = None,
+    allowed_types: Sequence[type] = SAFE_TYPES,
+):
+    """
+    Evaluate the Python expression `expr` using `eval`, but only if it is a safe expression in that its parsed AST
+    contains nodes whose types are given in `allowed_types`. This ensures unsafe node types are excluded, if these
+    are present in the AST a ValueError is raised. The default set of such types in `SAFE_TYPES` ensures only 
+    expressions with constants and names can be evaluated, so excludes attribute access, indexing, and calls. Code
+    injection is infeasible through such expressions, so this is a safe and secure way of evaluating simple expressions.
+
+    Args:
+        expr: expression to evaluate, this will be stripped before parsing to avoid indentation complaints
+        globals: global variable mapping
+        locals: local variable mapping
+        allows_types: sequence of allowed AST types which can be found in `expr` when parsed
+
+    Raises:
+        ValueError: raised when any node in the AST parsed from `expr` has a type not in `allowed_types`
+
+    Returns:
+        The evaluated expression value, using `eval` with `globals` and `locals`
+    """
+    parsed = ast.parse(expr.strip(), mode="eval")
+
+    def _disallowed_node(n):
+        return not any(isinstance(n, at) for at in allowed_types)
+
+    disallowed = list(filter(_disallowed_node, ast.walk(parsed)))
+
+    if disallowed:
+        disallowed_strs = list(map(ast.unparse, disallowed))
+        raise ValueError(
+            f"Unsafe expression `{expr}` cannot be evaluated, contains disallowed components: {disallowed_strs}"
+        )
+
+    return eval(expr, globals, locals)
diff --git a/tests/utils/test_safe_eval.py b/tests/utils/test_safe_eval.py
new file mode 100644
index 0000000000..fa2138471d
--- /dev/null
+++ b/tests/utils/test_safe_eval.py
@@ -0,0 +1,55 @@
+# Copyright (c) MONAI Consortium
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#     http://www.apache.org/licenses/LICENSE-2.0
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import ast
+import unittest
+from parameterized import parameterized
+
+from monai.utils import safe_eval
+
+GOOD_EXPRS = [
+    ("1+2", None, None, 3),
+    ("     1    +     2   ", None, None, 3),
+    ("1+2+x", {"x": 4}, None, 7),
+    ("1+2+x", None, {"x": 4}, 7),
+    ("1*2+x", {"x": 4}, None, 6),
+    ("(1+2)*3", None, None, 9),
+    ("foo+bar", {"foo": 1030}, {"bar": 204}, 1234),
+]
+
+BAD_EXPRS = [("foo()",), ("foo.bar",), ("foo[123]",), ("(1,2)",), ("[3,4]",), ("int.__class__.__init__.__globals__",)]
+
+
+class TestSafeEval(unittest.TestCase):
+    @parameterized.expand(GOOD_EXPRS)
+    def test_good_exprs(self, expr, globals, locals, expected):
+        """Test valid expressions with globals/locals evaluate to correct values."""
+        result = safe_eval(expr, globals, locals)
+        self.assertEqual(result, expected)
+
+    @parameterized.expand(BAD_EXPRS)
+    def test_bad_exprs(self, expr):
+        """Test bad expressions correctly raise ValueError."""
+        with self.assertRaises(ValueError):
+            safe_eval(expr)
+
+    def test_allowed_types(self):
+        """Test restricting the allowed list of types."""
+        allowed = [ast.Expression, ast.Constant, ast.BinOp, ast.Add]
+        result = safe_eval("1+2", allowed_types=allowed)
+        self.assertEqual(result, 3)
+
+        with self.assertRaises(ValueError):
+            safe_eval("1*2", allowed_types=allowed)
+
+
+if __name__ == "__main__":
+    unittest.main()

From 58e721e7971b0f325c398ad227135d104022ba56 Mon Sep 17 00:00:00 2001
From: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
Date: Sat, 20 Jun 2026 01:03:26 -0400
Subject: [PATCH 2/9] Remove eval where possible

Signed-off-by: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
---
 monai/bundle/scripts.py | 3 ++-
 monai/utils/ordering.py | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/monai/bundle/scripts.py b/monai/bundle/scripts.py
index ab02cd552e..b46d7930f5 100644
--- a/monai/bundle/scripts.py
+++ b/monai/bundle/scripts.py
@@ -51,6 +51,7 @@
     min_version,
     optional_import,
     pprint_edges,
+    safe_eval
 )
 
 validate, _ = optional_import("jsonschema", name="validate")
@@ -161,7 +162,7 @@ def _get_fake_spatial_shape(shape: Sequence[str | int], p: int = 1, n: int = 1,
                 for c in _get_var_names(i):
                     if c not in ["p", "n"]:
                         raise ValueError(f"only support variables 'p' and 'n' so far, but got: {c}.")
-                ret.append(eval(i, {"p": p, "n": n}))
+                ret.append(safe_eval(i, {"p": p, "n": n}))
         else:
             raise ValueError(f"spatial shape items must be int or string, but got: {type(i)} {i}.")
     return tuple(ret)
diff --git a/monai/utils/ordering.py b/monai/utils/ordering.py
index 1be61f98ab..012b744326 100644
--- a/monai/utils/ordering.py
+++ b/monai/utils/ordering.py
@@ -148,7 +148,7 @@ def _order_template(self, template: np.ndarray) -> np.ndarray:
         else:
             rows, columns, depths = (template.shape[0], template.shape[1], template.shape[2])
 
-        sequence = eval(f"self.{self.ordering_type}_idx")(rows, columns, depths)
+        sequence = getattr(self,f"{self.ordering_type}_idx")(rows, columns, depths)
 
         ordering = np.array([template[tuple(e)] for e in sequence])
 

From dd97330cd0852f62919c27b03acb9c79bc3d0430 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sat, 20 Jun 2026 05:05:30 +0000
Subject: [PATCH 3/9] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 monai/utils/safe_eval.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/monai/utils/safe_eval.py b/monai/utils/safe_eval.py
index 9c5293e229..220cf8f298 100644
--- a/monai/utils/safe_eval.py
+++ b/monai/utils/safe_eval.py
@@ -10,7 +10,8 @@
 # limitations under the License.
 
 import ast
-from typing import Any, Mapping, Sequence
+from typing import Any
+from collections.abc import Mapping, Sequence
 
 __all__ = ["SAFE_TYPES", "safe_eval"]
 
@@ -43,7 +44,7 @@ def safe_eval(
     """
     Evaluate the Python expression `expr` using `eval`, but only if it is a safe expression in that its parsed AST
     contains nodes whose types are given in `allowed_types`. This ensures unsafe node types are excluded, if these
-    are present in the AST a ValueError is raised. The default set of such types in `SAFE_TYPES` ensures only 
+    are present in the AST a ValueError is raised. The default set of such types in `SAFE_TYPES` ensures only
     expressions with constants and names can be evaluated, so excludes attribute access, indexing, and calls. Code
     injection is infeasible through such expressions, so this is a safe and secure way of evaluating simple expressions.
 

From f329f15bc080056fa95aafef6e9cd1781e014fe1 Mon Sep 17 00:00:00 2001
From: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
Date: Sat, 20 Jun 2026 01:13:41 -0400
Subject: [PATCH 4/9] Fixes

Signed-off-by: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
---
 monai/bundle/scripts.py       |  2 +-
 monai/utils/ordering.py       |  2 +-
 monai/utils/safe_eval.py      | 12 +++++++-----
 tests/utils/test_safe_eval.py |  7 +++++--
 4 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/monai/bundle/scripts.py b/monai/bundle/scripts.py
index b46d7930f5..1221460800 100644
--- a/monai/bundle/scripts.py
+++ b/monai/bundle/scripts.py
@@ -51,7 +51,7 @@
     min_version,
     optional_import,
     pprint_edges,
-    safe_eval
+    safe_eval,
 )
 
 validate, _ = optional_import("jsonschema", name="validate")
diff --git a/monai/utils/ordering.py b/monai/utils/ordering.py
index 012b744326..6daf5d4582 100644
--- a/monai/utils/ordering.py
+++ b/monai/utils/ordering.py
@@ -148,7 +148,7 @@ def _order_template(self, template: np.ndarray) -> np.ndarray:
         else:
             rows, columns, depths = (template.shape[0], template.shape[1], template.shape[2])
 
-        sequence = getattr(self,f"{self.ordering_type}_idx")(rows, columns, depths)
+        sequence = getattr(self, f"{self.ordering_type}_idx")(rows, columns, depths)
 
         ordering = np.array([template[tuple(e)] for e in sequence])
 
diff --git a/monai/utils/safe_eval.py b/monai/utils/safe_eval.py
index 220cf8f298..afdad04d27 100644
--- a/monai/utils/safe_eval.py
+++ b/monai/utils/safe_eval.py
@@ -9,9 +9,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
 import ast
-from typing import Any
 from collections.abc import Mapping, Sequence
+from typing import Any
 
 __all__ = ["SAFE_TYPES", "safe_eval"]
 
@@ -37,8 +39,8 @@
 
 def safe_eval(
     expr: str,
-    globals: Mapping[str, Any] | None = None,
-    locals: Mapping[str, object] | None = None,
+    globals_vars: Mapping[str, Any] | None = None,
+    locals_vars: Mapping[str, object] | None = None,
     allowed_types: Sequence[type] = SAFE_TYPES,
 ):
     """
@@ -52,7 +54,7 @@ def safe_eval(
         expr: expression to evaluate, this will be stripped before parsing to avoid indentation complaints
         globals: global variable mapping
         locals: local variable mapping
-        allows_types: sequence of allowed AST types which can be found in `expr` when parsed
+        allowed_types: sequence of allowed AST types which can be found in `expr` when parsed
 
     Raises:
         ValueError: raised when any node in the AST parsed from `expr` has a type not in `allowed_types`
@@ -73,4 +75,4 @@ def _disallowed_node(n):
             f"Unsafe expression `{expr}` cannot be evaluated, contains disallowed components: {disallowed_strs}"
         )
 
-    return eval(expr, globals, locals)
+    return eval(expr, globals_vars, locals_vars)
diff --git a/tests/utils/test_safe_eval.py b/tests/utils/test_safe_eval.py
index fa2138471d..bf0b0891c4 100644
--- a/tests/utils/test_safe_eval.py
+++ b/tests/utils/test_safe_eval.py
@@ -9,8 +9,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
 import ast
 import unittest
+
 from parameterized import parameterized
 
 from monai.utils import safe_eval
@@ -30,9 +33,9 @@
 
 class TestSafeEval(unittest.TestCase):
     @parameterized.expand(GOOD_EXPRS)
-    def test_good_exprs(self, expr, globals, locals, expected):
+    def test_good_exprs(self, expr, globals_vars, locals_vars, expected):
         """Test valid expressions with globals/locals evaluate to correct values."""
-        result = safe_eval(expr, globals, locals)
+        result = safe_eval(expr, globals_vars, locals_vars)
         self.assertEqual(result, expected)
 
     @parameterized.expand(BAD_EXPRS)

From 420d6102e7e0b9ad63259a07042374ac8f795880 Mon Sep 17 00:00:00 2001
From: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
Date: Sat, 20 Jun 2026 13:31:49 -0400
Subject: [PATCH 5/9] Minor fixes and renaming module to avoid alias test fail

Signed-off-by: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
---
 monai/utils/__init__.py                   |  2 +-
 monai/utils/{safe_eval.py => safeeval.py} | 23 +++++++++--------------
 tests/utils/test_alias.py                 |  5 ++++-
 3 files changed, 14 insertions(+), 16 deletions(-)
 rename monai/utils/{safe_eval.py => safeeval.py} (80%)

diff --git a/monai/utils/__init__.py b/monai/utils/__init__.py
index d0f4eb40ce..d1a705205c 100644
--- a/monai/utils/__init__.py
+++ b/monai/utils/__init__.py
@@ -137,7 +137,7 @@
     torch_profiler_time_cpu_gpu,
     torch_profiler_time_end_to_end,
 )
-from .safe_eval import SAFE_TYPES, safe_eval
+from .safeeval import SAFE_TYPES, safe_eval
 from .state_cacher import StateCacher
 from .tf32 import detect_default_tf32, has_ampere_or_later
 from .type_conversion import (
diff --git a/monai/utils/safe_eval.py b/monai/utils/safeeval.py
similarity index 80%
rename from monai/utils/safe_eval.py
rename to monai/utils/safeeval.py
index afdad04d27..e02239d4f4 100644
--- a/monai/utils/safe_eval.py
+++ b/monai/utils/safeeval.py
@@ -18,7 +18,7 @@
 __all__ = ["SAFE_TYPES", "safe_eval"]
 
 # default set of safe AST node types
-SAFE_TYPES = (
+SAFE_TYPES: Sequence[ast.AST] = (
     ast.Expression,
     ast.Name,
     ast.Load,
@@ -42,7 +42,7 @@ def safe_eval(
     globals_vars: Mapping[str, Any] | None = None,
     locals_vars: Mapping[str, object] | None = None,
     allowed_types: Sequence[type] = SAFE_TYPES,
-):
+) -> Any:
     """
     Evaluate the Python expression `expr` using `eval`, but only if it is a safe expression in that its parsed AST
     contains nodes whose types are given in `allowed_types`. This ensures unsafe node types are excluded, if these
@@ -52,27 +52,22 @@ def safe_eval(
 
     Args:
         expr: expression to evaluate, this will be stripped before parsing to avoid indentation complaints
-        globals: global variable mapping
-        locals: local variable mapping
+        globals_vars: global variable mapping
+        locals_vars: local variable mapping
         allowed_types: sequence of allowed AST types which can be found in `expr` when parsed
 
     Raises:
         ValueError: raised when any node in the AST parsed from `expr` has a type not in `allowed_types`
 
     Returns:
-        The evaluated expression value, using `eval` with `globals` and `locals`
+        The evaluated expression value, using `eval` with `globals_vars` and `locals_vars`
     """
     parsed = ast.parse(expr.strip(), mode="eval")
 
-    def _disallowed_node(n):
-        return not any(isinstance(n, at) for at in allowed_types)
-
-    disallowed = list(filter(_disallowed_node, ast.walk(parsed)))
+    # collect nodes in the AST which aren't permitted and unparse them for inclusion in the exception message
+    disallowed = [ast.unparse(n) for n in ast.walk(parsed) if not isinstance(n, tuple(allowed_types))]
 
     if disallowed:
-        disallowed_strs = list(map(ast.unparse, disallowed))
-        raise ValueError(
-            f"Unsafe expression `{expr}` cannot be evaluated, contains disallowed components: {disallowed_strs}"
-        )
+        raise ValueError(f"Unsafe expression `{expr}` not evaluated, contains disallowed components: {disallowed}")
 
-    return eval(expr, globals_vars, locals_vars)
+    return eval(expr, dict(globals_vars), locals_vars)
diff --git a/tests/utils/test_alias.py b/tests/utils/test_alias.py
index e7abff3d89..0e49cb406a 100644
--- a/tests/utils/test_alias.py
+++ b/tests/utils/test_alias.py
@@ -23,7 +23,10 @@
 
 
 class TestModuleAlias(unittest.TestCase):
-    """check that 'import monai.xx.file_name' returns a module"""
+    """
+    Check that 'import monai.xx.file_name' returns a module. Note that this test will fail if a module has the same name
+    as a member of that module (or any other) which is imported in a `__init__.py` file. 
+    """
 
     def test_files(self):
         src_dir = os.path.dirname(TESTS_PATH)

From 2f083a9744eb080354962aca29dd47a84a326a2d Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sat, 20 Jun 2026 17:32:08 +0000
Subject: [PATCH 6/9] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 tests/utils/test_alias.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/utils/test_alias.py b/tests/utils/test_alias.py
index 0e49cb406a..8ec1f8ae00 100644
--- a/tests/utils/test_alias.py
+++ b/tests/utils/test_alias.py
@@ -25,7 +25,7 @@
 class TestModuleAlias(unittest.TestCase):
     """
     Check that 'import monai.xx.file_name' returns a module. Note that this test will fail if a module has the same name
-    as a member of that module (or any other) which is imported in a `__init__.py` file. 
+    as a member of that module (or any other) which is imported in a `__init__.py` file.
     """
 
     def test_files(self):

From 23f9b250b3b667ee31c9ec623023f49717d8519f Mon Sep 17 00:00:00 2001
From: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
Date: Sat, 20 Jun 2026 13:41:06 -0400
Subject: [PATCH 7/9] Type tweak

Signed-off-by: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
---
 monai/utils/safeeval.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/monai/utils/safeeval.py b/monai/utils/safeeval.py
index e02239d4f4..33fa089a03 100644
--- a/monai/utils/safeeval.py
+++ b/monai/utils/safeeval.py
@@ -52,7 +52,7 @@ def safe_eval(
 
     Args:
         expr: expression to evaluate, this will be stripped before parsing to avoid indentation complaints
-        globals_vars: global variable mapping
+        globals_vars: global variable mapping, this will be treated as read-only for this function, unlike `eval`
         locals_vars: local variable mapping
         allowed_types: sequence of allowed AST types which can be found in `expr` when parsed
 
@@ -70,4 +70,4 @@ def safe_eval(
     if disallowed:
         raise ValueError(f"Unsafe expression `{expr}` not evaluated, contains disallowed components: {disallowed}")
 
-    return eval(expr, dict(globals_vars), locals_vars)
+    return eval(expr, dict(globals_vars) if globals_vars else None, locals_vars)

From 274c880e59741f1e2e071481c0184e6cf4bce118 Mon Sep 17 00:00:00 2001
From: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
Date: Sat, 20 Jun 2026 13:57:06 -0400
Subject: [PATCH 8/9] Type fix

Signed-off-by: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
---
 monai/utils/safeeval.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/monai/utils/safeeval.py b/monai/utils/safeeval.py
index 33fa089a03..358e964ef2 100644
--- a/monai/utils/safeeval.py
+++ b/monai/utils/safeeval.py
@@ -41,7 +41,7 @@ def safe_eval(
     expr: str,
     globals_vars: Mapping[str, Any] | None = None,
     locals_vars: Mapping[str, object] | None = None,
-    allowed_types: Sequence[type] = SAFE_TYPES,
+    allowed_types: Sequence[ast.AST] = SAFE_TYPES,
 ) -> Any:
     """
     Evaluate the Python expression `expr` using `eval`, but only if it is a safe expression in that its parsed AST

From 25d302bd4fbf2df1dc0fbb2dc0a33600a9f23aac Mon Sep 17 00:00:00 2001
From: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
Date: Sat, 20 Jun 2026 15:15:06 -0400
Subject: [PATCH 9/9] Picky typing issue

Signed-off-by: Eric Kerfoot <17726042+ericspod@users.noreply.github.com>
---
 monai/utils/safeeval.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/monai/utils/safeeval.py b/monai/utils/safeeval.py
index 358e964ef2..48fddfa07f 100644
--- a/monai/utils/safeeval.py
+++ b/monai/utils/safeeval.py
@@ -18,7 +18,7 @@
 __all__ = ["SAFE_TYPES", "safe_eval"]
 
 # default set of safe AST node types
-SAFE_TYPES: Sequence[ast.AST] = (
+SAFE_TYPES: Sequence[type] = (
     ast.Expression,
     ast.Name,
     ast.Load,
@@ -41,7 +41,7 @@ def safe_eval(
     expr: str,
     globals_vars: Mapping[str, Any] | None = None,
     locals_vars: Mapping[str, object] | None = None,
-    allowed_types: Sequence[ast.AST] = SAFE_TYPES,
+    allowed_types: Sequence[type] = SAFE_TYPES,
 ) -> Any:
     """
     Evaluate the Python expression `expr` using `eval`, but only if it is a safe expression in that its parsed AST