getRuleOperators() {
    const ret = [];
    const operators = this.rule.type.match(/[&|]/g) || '&';
    for (let i = 0; i < operators.length; i += 1) {
      ret.push(OPERATORS[operators[i]]);
    }
    return ret;
  }
Returns a list of the operators when multiple types given
its the case for example int|float
@private
@returns {[String]}