code: def test_explicit_downcast(self):
      f32 = jnp.float32(1.0)
      (x,) = dtypes.promote_dtype(f32, dtype=jnp.float16)
      self.assertEqual(x.dtype, jnp.float16)
  
file_path: flax/tests/linen/linen_dtypes_test.py
imports: import jax
  from absl.testing import absltest
  from jax import numpy
  from flax.linen import dtypes
label_desc: Use image node_id 3 for calling the DtypesTest obj's underlying member method code with example usage: obj.test_explicit_downcast() without return types