def _make_compound_key(table, key):
 if (not isinstance(key, (list, tuple))):
  key = [key]
 return [table.columns[name] for name in key]

def _make_compound_key ( table , key ) : if ( not isinstance ( key , ( list , tuple ) ) ) : key = [ key ] return [ table . columns [ name ] for name in key ]
returns a list of columns from column_key for table representing potentially a compound key .