docs: def get_gaf_gene_ontology_file(path):
      """Extract the gene ontology file associated with a GO annotation file.
  
      Parameters
      ----------
      path: str
          The path name of the GO annotation file.
  
      Returns
      -------
      str
          The URL of the associated gene ontology file.
      """
      assert isinstance(path, str)
  
      version = None
      with misc.smart_open_read(path, encoding='UTF-8', try_gzip=True) as fh:
          for l in fh:
              if l[0] != '!':
                  break
              if l.startswith('!GO-version:'):
                  version = l.split(' ')[1]
                  break
      return version