code: public ExpressionBuilder not(final ExpressionBuilder exp) {
  		// Note - NOT Expressions are not added to the stack (like the other group expressions AND and OR) and are
  		// treated the same as a "compare" expression.
  		// It is expected a NOT Expression is used by itself or with an AND or NOT.
  		GroupExpression not = new GroupExpression(Type.NOT);
  		not.add(exp.expression.getExpression());
  
  		appendExpression(not);
  
  		return this;
  	}
docs: Appends a NOT expression to this expression.
  
  @param exp the builder containing the expression to NOT with the current expression.
  @return this ExpressionBuilder.