def METHOD_NAME(xml):
    """Can turn off derivative of source terms"""
    pks = asearch.child_by_name(xml, "PKs")
    for pk in pks:
        try:
            source_term = pk.getElement("mass source key")
        except aerrors.MissingXMLError:
            pass
        else:
            source_term.setName('source key')
        try:
            source_term = pk.getElement("energy source key")
        except aerrors.MissingXMLError:
            pass
        else:
            source_term.setName('source key')
        try:
            source_term = pk.getElement("source term")
        except aerrors.MissingXMLError:
            pass
        else:
            if source_term.getValue():
                try:
                    source_is_diff = pk.getElement("source term is differentiable")
                except aerrors.MissingXMLError:
                    pk.append(parameter.BoolParameter("source term is differentiable", True))