code: def test_variable_equality_and_hash(f):
      shape = (2, 3, 4)
      x = nn.Variable(shape)
      assert f(x) == f(x)
  
      y = nn.Variable(shape)
      assert f(x) != f(y)
  
      y = x.get_unlinked_variable()
      assert f(x) == f(y)
  
      y.need_grad = True
      assert f(x) == f(y)
  
imports: import pytest
  import numpy
  import nnabla
  from nnabla.testing import assert_allclose
label_desc: Use image node_id 13 for calling a global function with example usage: test_variable_equality_and_hash(f) without return types