def _apply_validator_chain(chain, value, handler):

    if hasattr(chain, 'validate'):  # not a list
        chain = [chain, ]

    for validator in chain:
        if hasattr(validator, 'validate'):
            value = validator.validate(value, handler)
        else:
            raise web.HTTPError(500)
    return value
Apply validators in sequence to a value.
dataset/ETHPy150Open refinery29/chassis/chassis/util/params.py/_apply_validator_chain