docs: function isValidJSONPointer(pointer) {
    if (!_.isString(pointer)) {
        // If it's not a string, it obviously is not valid.
        return false;
    }
  
    // If it is string and is an empty string, it's valid.
    if ('' === pointer) {
        return true;
    }
  
    // If it is non-empty string, it must match spec defined format.
    // Check Section 3 of specification for concrete syntax.
    return validPointerRegex.test(pointer);
  }