def _find_exe(exe, paths=None):
    """Return path to an MSVC executable program.

    Tries to find the program in several places: first, one of the
    MSVC program search paths from the registry; next, the directories
    in the PATH environment variable.  If any of those work, return an
    absolute path that is known to exist.  If none of them work, just
    return the original program name, 'exe'.
    """
    if not paths:
        paths = os.getenv('path').split(os.pathsep)
    for p in paths:
        fn = os.path.join(os.path.abspath(p), exe)
        if os.path.isfile(fn):
            return fn
    return exe
Return path to an MSVC executable program.

    Tries to find the program in several places: first, one of the
    MSVC program search paths from the registry; next, the directories
    in the PATH environment variable.  If any of those work, return an
    absolute path that is known to exist.  If none of them work, just
    return the original program name, 'exe'.
    
product/gradle-plugin/src/main/python/setuptools/_distutils/_msvccompiler.py