code: def load_go_graph(go_fname):
      
      global _go_graph
      if _go_graph is None:
          _go_graph = rdflib.Graph()
          logger.info("Parsing GO OWL file")
          _go_graph.parse(os.path.abspath(go_fname))
      return _go_graph
docs: Load the GO data from an OWL file and parse into an RDF graph.
  
      Parameters
      ----------
      go_fname : str
          Path to the GO OWL file. Can be downloaded from
          http://geneontology.org/ontology/go.owl.
  
      Returns
      -------
      rdflib.Graph
          RDF graph containing GO data.