code: def _str_params(params):
      """Convert NoneType values to the string 'None' for display.
  
      Parameters
      ----------
      params : dict
          A dictionary of input values to a function.
  
      """
      params_str = copy.deepcopy(params)
      for k, v in params_str.items():
          if v is None:
              params_str[k] = "None"
      return params_str
  
imports: import copy
  import os
  import warnings
  from pathlib import Path
  from string import Template
  from nilearn.externals import tempita
  from nilearn.plotting.html_document import HTMLDocument
  from nilearn.reporting.utils import figure_to_svg_base64
label_desc: Use image node_id 3 for calling a global function with example usage: _str_params(params) and returns: params_str