code: def spo_search(self, subject=None, predicate=None, object=None):
          
          spo_query = '%s %s %s' % \
                  (self.spoencode(subject), self.spoencode(predicate), self.spoencode(object))
          return self.find_statements(spo_query)
docs: Create and run a subject-predicate-object (SPO) search.  Any search terms
          that are not specified will be replaced as a wildcard in the query.
  
          :param subject: optional subject to search
          :param predicate: optional predicate to search
          :param object: optional object to search
          :rtype: :class:`rdflib.ConjunctiveGraph`