code: def parse_identifiers_url(url):
      
      url_pattern = 'http://identifiers.org/([A-Za-z]+)/([A-Za-z0-9:]+)'
      match = re.match(url_pattern, url)
      if match is not None:
          g = match.groups()
          if not len(g) == 2:
              return (None, None)
          ns_map = {'hgnc': 'HGNC', 'uniprot': 'UP', 'chebi':'CHEBI',
                    'interpro':'IP', 'pfam':'XFAM', 'fplx': 'FPLX',
                    'go': 'GO', 'mesh': 'MESH', 'pubchem.compound': 'PUBCHEM'}
          ns = g[0]
          id = g[1]
          if not ns in ns_map.keys():
              return (None, None)
          if ns == 'hgnc':
              if id.startswith('HGNC:'):
                  id = id[5:]
              else:
                  logger.warning('HGNC URL missing "HGNC:" prefix: %s' % url)
                  return (None, None)
          indra_ns = ns_map[ns]
          return (indra_ns, id)
      return (None, None)
docs: Parse an identifiers.org URL into (namespace, ID) tuple.