applyPrefix(prefixes, value) {
        // console.log('applyPrefix', prefixes, value);
        if (this.context.async) {
            return this.applyPrefixAsync(prefixes, value);
        } else {
            const {val, isArray} = this.extractRefValue(value);
            return this._applyPrefix(prefixes, val, isArray);
        }
    }
Apply + or - unary prefix.
@param {Array.<string>} prefixes
@param {*} value
@return {*}