def p_modifies(p):
    p[0] = None
Getting the keys of a form yields a list of field names.
dataset/ETHPy150Open Microsoft/ivy/src/ivy/ivy_dafny_grammar.py/p_modifies--crossover with--dataset/ETHPy150Open ralphm/wokkel/wokkel/test/test_data_form.py/FormTest.test_keys