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 forward(self, x):
      return npx.activation(x, act_type=self._act_type, name="fwd")
  
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 3 for calling the Activation obj's underlying member method code with example usage: obj.forward(x) and returns: npx