Python Version - Decent way of auto incrementing the version of a Python script based on the tags in the Git repo

ver.py

import subprocess

# what to put if version cannot be determined
_undefined_version = "undefined version"

# first, try getting version from git
_git_version = None
try:
    _git_version = subprocess.check_output(["git", "describe", "--dirty"], stderr=subprocess.PIPE).strip().decode("utf-8")
except (FileNotFoundError, subprocess.CalledProcessError) as e:
    pass  # git is not installed, or can't get the version.

# second, try getting version from the _version.py file
_file_version = None
try:
    from _version import version as _file_version
except (ModuleNotFoundError, AttributeError):
    pass

# third, see if we need to write the version file
if _git_version and (not _file_version or _git_version != _file_version):
    # if the git version exists, and the file version either doesn't exist or doesn't match
    with open("_version.py", "w") as file:
        file.write(f'version = "{_git_version}"')

# fourth, set the version
version = _git_version or _file_version or _undefined_version

if __name__ == "__main__":
    print(version, end="")