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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def certify_required(value, required=False):
 """ Certify that a value is present if required. :param object value: The value that is to be certified. :param bool required: Is the value required? :raises CertifierValueError: Required value is `None`. """

    # Certify our kwargs:
    if not isinstance(required, bool):
        raise CertifierParamError(
            'required',
            required,
        )
    if value is None:
        if required:
            raise CertifierValueError(
                message="required value is None",
            )
        return True