docs: function parseHeader(req) {
  
      if (req.headers && req.headers.authorization) {
  
          var credentialsIndex = 1;
          var parts = req.headers.authorization.split(' ');
          var partsExpectedLength = 2;
          var schemeIndex = 0;
  
          if (parts.length === partsExpectedLength) {
  
              var credentials = parts[credentialsIndex];
              var scheme = parts[schemeIndex];
  
              if (/^Bearer$/i.test(scheme)) {
                  return credentials;
              }
  
          }
  
      }
  
      return null;
  
  }