Function isSubplotId

src/lib/coerce.js:235–235

        coerceFunction: function(v, propOut, dflt, opts) {
            var regex = opts.regex || counterRegex(dflt);
            const isSubplotId = value => typeof value === 'string' && regex.test(value);
            if (isSubplotId(v) || (opts.arrayOk && isArrayOrTypedArray(v) && v.length > 0 && v.every(isSubplotId))) {
                propOut.set(v);
            } else {