code: def Softplus():
      r"""Returns a layer that computes the softplus function.
  
      .. math::
          f(x) = \ln(e^x + 1)
      """
      return Fn("Softplus", lambda x: jnp.logaddexp(x, 0.0))
  
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 12 for calling a global function with example usage: Softplus() and returns: Fn