class_docstr: General purpose scheduler for parameters values. By default it can schedule in a linear, exponential, step or
  multistep function. One can also pass Callables to have customized scheduling logic.
  
  Args:
      parameter_setter (Callable): Function that sets the required parameter
      value_calculator (Union[str,Callable]): Either a string ('linear', 'exponential', 'step' or 'multistep')
       or Callable for custom logic.
      vc_kwargs (Dict): Dictionary that stores the required parameters for the value_calculator.
      epoch_level (bool): Whether the step is based on epoch or iteration. Defaults to False.
      name (Optional[str]): Identifier of logging.logger to use, if None, defaulting to ``engine.logger``.
      event (Optional[str]): Event to which the handler attaches. Defaults to Events.ITERATION_COMPLETED.
code: def _get_value_calculator(self, value_calculator):
      if isinstance(value_calculator, str):
          return self._calculators[value_calculator]
      if callable(value_calculator):
          return value_calculator
      raise ValueError(
          f"value_calculator must be either a string from {list(self._calculators.keys())} or a Callable."
      )
  
file_path: MONAI/monai/handlers/parameter_scheduler.py
imports: from __future__ import annotations
  import logging
  from bisect import bisect_right
  from collections.abc import Callable
  from typing import TYPE_CHECKING
  from monai.config import IgniteInfo
  from monai.utils import min_version, optional_import
label_desc: Use image node_id 2 for calling the ParamSchedulerHandler obj's underlying member method code with example usage: obj._get_value_calculator(value_calculator) and returns: self, value_calculator