code: def _clean_contrast_name(contrast_name):
      """Remove prohibited characters from name and convert to camelCase.
  
      .. versionadded:: 0.9.2
  
      BIDS filenames, in which the contrast name will appear as a
      contrast-<name> key/value pair, must be alphanumeric strings.
  
      Parameters
      ----------
      contrast_name : :obj:`str`
          Contrast name to clean.
  
      Returns
      -------
      new_name : :obj:`str`
          Contrast name converted to alphanumeric-only camelCase.
      """
      new_name = contrast_name[:]
  
      # Some characters translate to words
      new_name = new_name.replace("-", " Minus ")
      new_name = new_name.replace("+", " Plus ")
      new_name = new_name.replace(">", " Gt ")
      new_name = new_name.replace("<", " Lt ")
  
      # Others translate to spaces
      new_name = new_name.replace("_", " ")
  
      # Convert to camelCase
      new_name = new_name.split(" ")
      new_name[0] = new_name[0].lower()
      new_name[1:] = [c.title() for c in new_name[1:]]
      new_name = " ".join(new_name)
  
      # Remove non-alphanumeric characters
      new_name = "".join(ch for ch in new_name if ch.isalnum())
  
      # Let users know if the name was changed
      if new_name != contrast_name:
          warnings.warn(
              f'Contrast name "{contrast_name}" changed to "{new_name}"'
          )
      return new_name
  
file_path: nilearn/nilearn/interfaces/bids/glm.py
imports: import json
  import os
  import warnings
  import numpy
  from nilearn import __version__
label_desc: Use image node_id 1 for calling a global function with example usage: _clean_contrast_name(contrast_name) and returns: new_name