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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 is_valid(self):
 """Tests if ths form is in a valid state for submission. A form is valid if all required data has been supplied compliant with any constraints. return: (boolean) - false if there is a known error in this form, true otherwise raise: OperationFailed - attempt to perform validation failed compliance: mandatory - This method must be implemented. """

        validity = True
        for element in self._validity_map:
            if self._validity_map[element] is not VALID:
                validity = False
        return validity