Evaluates a file containing a Python params dictionary.

def eval_py(self, _globals, _locals):
        """
        Evaluates a file containing a Python params dictionary.
        """
        try:
            params = eval(self.script, _globals, _locals)
        except NameError as e:
            raise Exception(
                'Failed to evaluate parameters: {}'
                .format(str(e))
            )
        except ResolutionError as e:
            raise Exception('GetOutput: {}'.format(str(e)))

        return params