class_docstr: Applies an activation function to input.
  
  Parameters
  ----------
  activation : str
      Name of activation function to use.
      See :func:`~mxnet.ndarray.Activation` for available choices.
  
  
  Inputs:
      - **data**: input tensor with arbitrary shape.
  
  Outputs:
      - **out**: output tensor with the same shape as `data`.
code: def __repr__(self):
      s = "{name}({_act_type})"
      return s.format(name=self.__class__.__name__, **self.__dict__)
  
imports: from ...None import initializer, npx
  from ..block import HybridBlock
  from ..parameter import Parameter
  from ...util import use_np
label_desc: Use image node_id 4 for calling the Activation obj's underlying member method code with example usage: obj.__repr__() and returns: s