code: function getMatcher(f) {
    if (!isPrimitive(f)) {
      var className = classToString(f);
      if (isRegExp(f, className)) {
        return regexMatcher(f);
      } else if (isDate(f, className)) {
        return dateMatcher(f);
      } else if (isFunction(f, className)) {
        return functionMatcher(f);
      } else if (isPlainObject(f, className)) {
        return fuzzyMatcher(f);
      }
    }
    // Default is standard isEqual
    return defaultMatcher(f);
  }
docs: Fuzzy matching helpers