public static boolean isNegation(@Nullable PsiExpression expression) {
    expression = PsiUtil.skipParenthesizedExprDown(expression);
    if (expression instanceof PsiPrefixExpression) return isUnaryNegation((PsiPrefixExpression)expression);
    if (expression instanceof PsiPolyadicExpression) return isBinaryNegation((PsiPolyadicExpression)expression);
    return false;
  }
public static boolean isNegation(@Nullable PsiExpression expression)