code: def Gelu():
      r"""Returns a layer that computes the Gaussian Error Linear Unit function.
  
      .. math::
          f(x) = \frac{x}{2} \cdot (1 + \hbox{erf}(\frac{x}{\sqrt{2}}))
      """
      return Fn(
          "Gelu",
          lambda x: x * 0.5 * (1.0 + fastmath.erf(x / jnp.sqrt(2.0))),
      )
  
imports: from trax import fastmath
  from trax.fastmath import numpy
  from trax.layers import base
  from trax.layers.assert_shape import assert_shape
  from trax.layers.base import Fn
label_desc: Use image node_id 6 for calling a global function with example usage: Gelu() and returns: Fn