code: def escape_fn_name(name):
      ret = "".join([i if i in _varname_charset else "_" for i in name])
      ret = escape_name(name)
      if ret.startswith("f_"):
          return ret
      else:
          return "f_" + ret
  
label_desc: Use image node_id 2 for calling a global function with example usage: escape_fn_name(name) and returns: ret, unknown