def METHOD_NAME(Comp):
    """Check that fields are defined at valid locations"""
    component_name = Comp._name
    # verify all info exist:
    for name, meta in Comp._info.items():
        at = meta["mapping"]
        # TODO: Verify that all units are UDUNITS compatible.
        if at not in _VALID_LOCS:
            raise ValueError(
                f"{component_name} mapping for variable: {name} is invalid: {at}"
            )