code: def test_flatten_unflatten():
      """Test the behavior of the flatten and unflatten methods."""
      weights = np.array([[0.1, -2.1, 1.4]])
      op = qml.RandomLayers(weights, wires=(0, 1))
  
      data, metadata = op._flatten()
  
      assert qml.math.allclose(data[0], weights)
      # check metadata hashable
      assert hash(metadata)
  
      new_op = type(op)._unflatten(*op._flatten())
      assert qml.equal(new_op, op)
      assert new_op is not op
  
imports: import pytest
  import numpy
  import pennylane
  from pennylane import numpy
label_desc: Use image node_id 3 for calling a global function with example usage: test_flatten_unflatten() without return types