get(key, default=None)
  Return the parameter associated with key if present. Otherwise
  return default if provided, None if not.

  Parameters:
     * **key** (*str*) -- key to get from the ParameterDict

     * **default** (*Parameter**, **optional*) -- value to return
       if key not present

  Return type:
     *Any*

items()
  Return an iterable of the ParameterDict key/value pairs.

  Return type:
     *Iterable*[*Tuple*[str, *Any*]]

keys()
  Return an iterable of the ParameterDict keys.

  Return type:
     *Iterable*[str]

pop(key)
  Remove key from the ParameterDict and return its parameter.

  Parameters:
     **key** (*str*) -- key to pop from the ParameterDict

  Return type:
     *Any*

popitem()
  Remove and return the last inserted *(key, parameter)* pair from
  the ParameterDict

  Return type:
     *Tuple*[str, *Any*]

setdefault(key, default=None)