docs: def get_raw_column(table_name, column_name):
      """
      Get a wrapped, registered column.
  
      This function cannot return columns that are part of wrapped
      DataFrames, it's only for columns registered directly through Orca.
  
      Parameters
      ----------
      table_name : str
      column_name : str
  
      Returns
      -------
      wrapped : _SeriesWrapper or _ColumnFuncWrapper
  
      """
      try:
          return _COLUMNS[(table_name, column_name)]
      except KeyError:
          raise KeyError('column {!r} not found for table {!r}'.format(
              column_name, table_name))