posixpath.py 文件源码

def normcase(s):
    """Normalize case of pathname.  Has no effect under Posix"""
    s = os.fspath(s)
    if not isinstance(s, (bytes, str)):
        raise TypeError("normcase() argument must be str or bytes, "
                        "not '{}'".format(s.__class__.__name__))
    return s


# Return whether a path is absolute.
# Trivial in Posix, harder on the Mac or MS-DOS.