code: def _check_init_parameter_variables(variables: Variables) -> Any:
      """
      Checks that the input is of the correct type. Allowed  values are None, int, str or
      list of strings and ints.
  
      Parameters
      ----------
      variables : string, int, list of strings, list of integers. Default=None
  
      Returns
      -------
      variables: same as input
      """
  
      msg = "variables should be a string, an int or a list of strings or integers."
      msg_dupes = "the list contains duplicated variable names"
  
      if variables:
          if isinstance(variables, list):
              if not all(isinstance(i, (str, int)) for i in variables):
                  raise ValueError(msg)
              if len(variables) != len(set(variables)):
                  raise ValueError(msg_dupes)
          else:
              if not isinstance(variables, (str, int)):
                  raise ValueError(msg)
  
      return variables
  
label_desc: Use image node_id 1 for calling a global function with example usage: _check_init_parameter_variables(variables) and returns: variables