static _toggleNegativeBracket(value, settings, isFocused) {
        //XXX Note; this function is static since we need to pass a `settings` object when calling the static `AutoNumeric.format()` method
        let result;
        if (isFocused) {
            result = this._removeBrackets(value, settings);
        } else {
            result = this._addBrackets(value, settings);
        }

        return result;
    }
Sets or removes brackets on negative values, depending on the focus state, which is passed as `isFocused`.
The focus state is 'stored' in that object property.

@param {string} value
@param {object} settings
@param {boolean} isFocused
@returns {*}