code: def test_cast_assignment(self):
      a = Tensor(np.arange(N * N, dtype=np.float32)).reshape(N, N)
      a.realize()
      oba1 = a.lazydata.base.output_buffer
      a.assign(a.cast(dtypes.int32).realize())
      a.realize()
      oba2 = a.lazydata.base.output_buffer
      assert oba1 is None and oba2 is None
      np.testing.assert_allclose(
          a.numpy(), np.arange(N * N, dtype=np.int32).reshape((N, N))
      )
  
file_path: tinygrad/test/test_assign.py
imports: import unittest
  import numpy
  from tinygrad.tensor import Tensor
  from tinygrad import Device, dtypes
label_desc: Use image node_id 4 for calling the TestAssign obj's underlying member method code with example usage: obj.test_cast_assignment() without return types