code: def Elu(a=1.0):
      r"""Returns a ReLU-like layer with exponential outputs for negative inputs.
  
    .. math::
        f(x) = \left\{ \begin{array}{cl}
            a \cdot (e^x - 1) & \text{if}\ x \leq 0, \\
            x                 & \text{otherwise}.
        \end{array} \right.
  
    (Asymptotically, :math:`f(x)\rightarrow -a` as :math:`x\rightarrow - \infty`.)
  
    Args:
      a: Coefficient multiplying the exponential, for negative inputs.
    """
      return Fn("Elu", lambda x: jnp.where(x > 0, x, a * jnp.expm1(x)))
  
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 4 for calling a global function with example usage: Elu(a) and returns: Fn