Hoist os, posixpath and urllib.parse to module-level lazy imports

Per review: place the lazy imports at the top of the module with the other
imports, above the platform try/except blocks, instead of inside the
functions, and drop the now-redundant 'Lazy import to improve module import
time' comments.

Author: gaborbernat

Lib/mimetypes.py

@@ -23,6 +23,10 @@
 read_mime_types(file) -- parse one file, return a dictionary or None
 """
 
+lazy import os
+lazy import posixpath
+lazy import urllib.parse
+
 try:
     from _winapi import _mimetypes_read_windows_registry
 except ImportError:
@@ -33,8 +37,6 @@
 except ImportError:
     _winreg = None
 
-lazy import urllib.parse
-
 __all__ = [
     "knownfiles", "inited", "MimeTypes",
     "guess_type", "guess_file_type", "guess_all_extensions", "guess_extension",
@@ -123,9 +125,6 @@ def guess_type(self, url, strict=True):
         Optional 'strict' argument when False adds a bunch of commonly found,
         but non-standard types.
         """
-        # Lazy import to improve module import time
-        import os
-
         # TODO: Deprecate accepting file paths (in particular path-like objects).
         url = os.fspath(url)
         # Without a ':' the argument cannot carry a URL scheme, so it cannot
@@ -159,19 +158,13 @@ def guess_type(self, url, strict=True):
                 type = 'text/plain'
             return type, None           # never compressed, so encoding is None
 
-        # Lazy import to improve module import time
-        import posixpath
-
         return self._guess_file_type(url, strict, posixpath.splitext)
 
     def guess_file_type(self, path, *, strict=True):
         """Guess the type of a file based on its path.
 
         Similar to guess_type(), but takes file path instead of URL.
         """
-        # Lazy import to improve module import time
-        import os
-
         path = os.fsdecode(path)
         path = os.path.splitdrive(path)[1]
         return self._guess_file_type(path, strict, os.path.splitext)
@@ -418,9 +411,6 @@ def init(files=None):
     else:
         db = _db
 
-    # Lazy import to improve module import time
-    import os
-
     for file in files:
         if os.path.isfile(file):
             db.read(file)