if (argumentList == null) return null;
GroovyPsiElement[] arguments = argumentList.getAllArguments();
if (arguments.length == 0 || arguments.length > 2) return null;
GroovyPsiElement arg = arguments[0];
if (!(arg instanceof GrUnaryExpression && ((GrUnaryExpression)arg).getOperationTokenType() == GroovyTokenTypes.mBNOT)) return null;
GrExpression operand = ((GrUnaryExpression)arg).getOperand();
if (!(operand instanceof GrLiteral)) return null;