code: def _find_assignment(arg_token):
      
      idx = arg_token.find("=")
      while idx != -1:
          if idx != 0 and arg_token[idx - 1] != "\\":
              # No escape character
              return idx
  
          idx = arg_token.find("=", idx + 1)
  
      # No assignment found
      return -1
docs: Find the first non-escaped assignment in the given argument token.
      Returns -1 if no assignment was found.
  
      :param arg_token: The argument token
      :return: The index of the first assignment, or -1