code: def _extract_core_semantics(self, docs):
          
          all_concepts = []
          doc_core_sems = []
          for doc in docs:
              core_sems = self._process_doc(doc)
              doc_core_sems.append(core_sems)
              all_concepts += [con for con, weight in core_sems]
          return doc_core_sems, list(set(all_concepts))
docs: Extracts core semantics for a list of documents, returning them along with
          a list of all the concepts represented.