def url2pathname(pathname):
    #
    # XXXX The .. handling should be fixed...
    #
    tp = urllib.splittype(pathname)[0]
    if tp and tp != 'file':
        raise RuntimeError, 'Cannot convert non-local URL to pathname'
    # Turn starting /// into /, an empty hostname means current host
    if pathname[:3] == '///':
        pathname = pathname[2:]
    elif pathname[:2] == '//':
        raise RuntimeError, 'Cannot convert non-local URL to pathname'
    components = pathname.split('/')
    # Remove . and embedded ..
    i = 0
    while i < len(components):
        if components[i] == '.':
            del components[i]
        elif components[i] == '..' and i > 0 and \
                                  components[i-1] not in ('', '..'):
            del components[i-1:i+1]
            i = i-1
        elif components[i] == '' and i > 0 and components[i-1] != '':
            del components[i]
        else:
            i = i+1
    if not components[0]:
        # Absolute unix path, don't start with colon
        rv = ':'.join(components[1:])
    else:
        # relative unix path, start with colon. First replace
        # leading .. by empty strings (giving ::file)
        i = 0
        while i < len(components) and components[i] == '..':
            components[i] = ''
            i = i + 1
        rv = ':' + ':'.join(components)
    # and finally unquote slashes and other funny characters
    return urllib.unquote(rv)
OS-specific conversion from a relative URL of the 'file' scheme
dataset/ETHPy150Open Southpaw-TACTIC/TACTIC/src/context/client/tactic-api-python-4.0.api04/Lib/macurl2path.py/url2pathname