code: def _dataframe_to_vertex_list(df):
      
      cols = df.columns
      if len(cols):
          assert _VID_COLUMN in cols, "Vertex DataFrame must contain column %s" % _VID_COLUMN
          df = df[cols].T
          ret = [Vertex(None, _series=df[col]) for col in df]
          return ret
      else:
          return []
docs: Convert dataframe into list of vertices, assuming that vertex ids are stored in _VID_COLUMN.