def _coerce_field_name(field_name, field_index):
 if callable(field_name):
  if (field_name.__name__ == '<lambda>'):
   return ('lambda' + str(field_index))
  else:
   return field_name.__name__
 return field_name

def _coerce_field_name ( field_name , field_index ) : if callable ( field_name ) : if ( field_name . __name__ == '<lambda>' ) : return ( 'lambda' + str ( field_index ) ) else : return field_name . __name__ return field_name
coerce a field_name to a string .