class_docstr: Defines how to configure an optimizer.
  
  For each train step it returns a dictionary that contains the configuration for the optimizer.
  
  Args:
      lr (List[float], optional): a configuration space for the learning rate.
      momentum (List[float], optional): a configuration space for the momentum.
class_docstr_tok: ["Defines","how","to","configure","an","optimizer",".","For","each","train","step","it","returns","a","dictionary","that","contains","the","configuration","for","the","optimizer",".","Args",":","lr","(","List","[","float","]",",","optional",")",":","a","configuration","space","for","the","learning","rate",".","momentum","(","List","[","float","]",",","optional",")",":","a","configuration","space","for","the","momentum","."]
docstr: Plot the phase for the given `param_name`.
  
  Args:
      param_name (str, optional): the name of the parameter to plot.
      ax (~matplotlib.pyplot.axis, optional): a matplotlib axis to plot on, if given.
  
  Returns:
      The matplotlib axis.
docstr_tok: ["Plot","the","phase","for","the","given","`","param_name","`",".","Args",":","param_name","(","str",",","optional",")",":","the","name","of","the","parameter","to","plot",".","ax","(","~matplotlib.pyplot.axis",",","optional",")",":","a","matplotlib","axis","to","plot","on",",","if","given",".","Returns",":","The","matplotlib","axis","."]
code: def plot(self, param_name: str = "lr", ax=None):
      """
      Plot the phase for the given `param_name`.
  
      Args:
          param_name (str, optional): the name of the parameter to plot.
          ax (~matplotlib.pyplot.axis, optional): a matplotlib axis to plot on, if given.
  
      Returns:
          The matplotlib axis.
      """
      # pylint: disable=import-error
  
      if ax is None:
          _fig, ax = plt.subplots()
  
      ax.plot(list(self.configuration[param_name]))
      ax.set_xlabel("steps")
      ax.set_ylabel(param_name)
      return ax
  
imports: import contextlib
  from collections import OrderedDict
  from itertools import chain, islice
  from math import cos, pi
  from typing import Dict, List, Optional, Tuple
  from poutyne.framework.callbacks.callbacks import Callback
label_desc: Use image node_id 4 for calling the Phase obj's underlying member method code with example usage: obj.plot(param_name, ax) and returns: ax