code: def _vertex_list_to_dataframe(ls, id_column_name):
      
      assert HAS_PANDAS, 'Cannot use dataframe because Pandas is not available or version is too low.'
      cols = reduce(set.union, (set(v.attr.keys()) for v in ls))
      df = pd.DataFrame({id_column_name: [v.vid for v in ls]})
      for c in cols:
          df[c] = [v.attr.get(c) for v in ls]
      return df
docs: Convert a list of vertices into dataframe.