docstr: Test the _flatten and _unflatten methods for ControlledSequence
docstr_tok: ["Test","the","_flatten","and","_unflatten","methods","for","ControlledSequence"]
code: def test_flatten_and_unflatten(self):
      """Test the _flatten and _unflatten methods for ControlledSequence"""
  
      op = qml.ControlledSequence(
          qml.RX(0.25, wires=3), control=[0, 1, 2]
      )
      data, metadata = op._flatten()
  
      assert len(data) == 1
      assert qml.equal(data[0], op.base)
  
      assert len(metadata) == 1
      assert metadata[0] == op.control
  
      # make sure metadata is hashable
      assert hash(metadata)
  
      new_op = type(op)._unflatten(*op._flatten())
  
      assert qml.equal(op.base, new_op.base)
      assert op.control_wires == new_op.control_wires
      assert op is not new_op
  
imports: import pytest
  import numpy
  from pennylane import numpy
  import pennylane
  from pennylane.wires import Wires
label_desc: Use image node_id 2 for calling the TestInitialization obj's underlying member method code with example usage: obj.test_flatten_and_unflatten() without return types