_getFullName(user, repo) {
      let fullname = user;

      if (repo) {
         fullname = `${user}/${repo}`;
      }

      return fullname;
   }
Computes the full repository name
@param {string} user - the username (or the full name)
@param {string} repo - the repository name, must not be passed if `user` is the full name
@return {string} the repository's full name