api/users/getUserTweets.rb
get '/api/v1/users/:user_id/tweets' do
# Just means return recent n tweets.
n = 20
userRecentTweets(params[:user_id],n).to_json
end
def userRecentTweets(theId,n)
# descend: show new tweets first.
Tweet.where(user_id: theId).order(create_time: :desc).limit(n)
end