code: def _columns_for_table(table_name):
      
      return {cname: col
              for (tname, cname), col in _COLUMNS.items()
              if tname == table_name}
docs: Return all of the columns registered for a given table.
  
      Parameters
      ----------
      table_name : str
  
      Returns
      -------
      columns : dict of column wrappers
          Keys will be column names.