class_docstr: Base layer class.
  
  Parameters
  ----------
  input_size : list
      size of the layer input
  output_size : list
      size of the layer output
  activation : str or None
      activation function name
  input_index_mapper : IndexMapper or None
      map indexes from this layer index to the input layer index size
docstr: Change the activation function
docstr_tok: ["Change","the","activation","function"]
code: def activation(self, new_activation):
      """Change the activation function"""
      if new_activation is None:
          new_activation = "linear"
      self.__activation = new_activation
  
imports: import itertools
  import numpy
label_desc: Use image node_id 5 for calling the Layer obj's underlying member method code with example usage: obj.activation(new_activation) without return types