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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 errors(self):
 """ Returns a TupleErrorList for this field. This overloaded method adds additional error lists to the errors as detected by the form validator. """

        if not hasattr(self, '_errors_cache'):
            self._errors_cache = self.form.get_field_errors(self)
        return self._errors_cache