def METHOD_NAME(p, token, left, rbp):
  # type: (tdop.Parser, tdop.Token, arith_expr_t, int) -> arith_expr_t
  """ Normal binary operator like 1+2 or 2*3, etc. """
  # x += 1, or a[i] += 1
  if not isinstance(left, (arith_expr.Var, arith_expr.Index)):
    raise tdop.ParseError("Can't assign to %r" % left)
  node = arith_expr.Binary(token.val, left, p.ParseUntil(rbp))
  return node