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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 _write_avg_norm(self, norms:[])->None:
        "Writes the average norm of the gradients to Tensorboard."
        avg_norm = sum(norms)/len(self.gradients)
        self._add_gradient_scalar('avg_norm', scalar_value=avg_norm)