def py_to_val(pyval):
    if isinstance(pyval, bool):
        return 'true' if pyval is True else 'false'
    elif pyval == '':
        return '""'
    else:
        return pyval
Return the set of discourse referents in this DRS.
dataset/ETHPy150Open openstack/neutron/neutron/agent/ovsdb/api.py/py_to_val--crossover with--dataset/ETHPy150Open nltk/nltk/nltk/sem/drt.py/DrtExpression.get_refs