docs: function oauth2TokenParser(options) {
  
      function parseOauth2Token(req, res, next) {
          req.oauth2 = { accessToken: null};
  
          var tokenFromHeader = parseHeader(req);
  
          if (tokenFromHeader) {
  
              req.oauth2.accessToken = tokenFromHeader;
          }
  
          var tokenFromBody = null;
  
          if (typeof req.body === 'object') {
              tokenFromBody = req.body.access_token;
          }
  
          // more than one method to transmit the token in each request
          // is not allowed - return 400
          if (tokenFromBody && tokenFromHeader) {
              return next(new errors.makeErrFromCode(400,
                  'multiple tokens disallowed'));
          }
  
          if (tokenFromBody && req.contentType().toLowerCase()
              === 'application/x-www-form-urlencoded') {
              req.oauth2.accessToken = tokenFromBody;
          }
  
          return (next());
      }
  
      return (parseOauth2Token);
  }