docs: def load_var_files(opt, p_obj=None):
      """Load variable files, merge, return contents"""
      obj = {}
      if p_obj:
          obj = p_obj
  
      for var_file in opt.extra_vars_file:
          LOG.debug("loading vars from %s", var_file)
          obj = merge_dicts(obj.copy(), load_var_file(var_file, obj))
  
      return obj