code: def assign_sub(
      self, delta, use_locking=None, name=None, read_value=True
  ):
      ivy.utils.assertions.check_equal(
          delta.shape
          if hasattr(delta, "ivy_array")
          else ivy.shape(delta),
          self.shape,
          as_array=False,
      )
      self._ivy_array = tf_frontend.math.subtract(
          self._ivy_array, delta._ivy_array
      )
  
imports: import ivy
  import ivy.functional.frontends.tensorflow
label_desc: Use image node_id 9 for calling the Variable obj's underlying member method code with example usage: obj.assign_sub(delta, use_locking, name, read_value) without return types