private static boolean isIdentity(PsiExpression operand, String opSign) {
    return "+".equals(opSign) && ExpressionUtils.isZero(operand) ||
           "*".equals(opSign) && ExpressionUtils.isOne(operand) ||
           "^".equals(opSign) && ExpressionUtils.isLiteral(operand, false) ||
           "|".equals(opSign) && ExpressionUtils.isLiteral(operand, false) ||
           "&".equals(opSign) && ExpressionUtils.isLiteral(operand, true);
  }
private static boolean isIdentity(PsiExpression operand, String opSign)