code: def parse_pac_file(pacfile):
    
    try:
      with open(pacfile) as f:
        pac_script = f.read()
        _pacparser.parse_pac_string(pac_script)
    except IOError:
      raise IOError('Could not read the pacfile: {}'.format(pacfile))
docs: Reads the pacfile and evaluates it in the Javascript engine created by
    init().