@Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        if (result != null) {
            sb.append(result).append(" = ");
        }
        return sb.append(function).toString();
    }
Gets the function used to express this condition.

@return the function for this condition.
smithy-rules-engine/src/main/java/software/amazon/smithy/rulesengine/language/syntax/rule/Condition.java