def ensure_user(data)
      if @users.include?(data['id'].to_i)
        @users[data['id'].to_i]
      else
        @users[data['id'].to_i] = User.new(data, self)
      end
    end
def ensure_user(data)
      if @users.include?(data['id'].to_i)
        @users[data['id'].to_i]
      else
        @users[data['id'].to_i] = User.new(data, self)
      end
    end
Ensures a given user object is cached and if not, cache it from the given data hash.
 @param data [Hash] A data hash representing a user.
 @return [User] the user represented by the data hash.