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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 storage_del(self, key=None):
 """ Remove the value stored with the key from storage. If key is not supplied then all values for the module are removed. """

        if not self._module:
            return
        self._storage_init()
        module_name = self._module.module_full_name
        return self._storage.storage_del(module_name, key=key)