Claim : Struct for save the JWT data.

LoginResponse : Save the login token.

Relation : Model of the relation between users (follow).

ResponseCheckRelation : Got the response from the database when check if two user got a relationship.

ReturnTweet : Struct for return a tweet.

ReturnTweetsFollowers : Struct for the tweets.

SaveTweet : Struct for tweets model.

Tweet : Struct for tweet that came from the r.Body.

User : Struct for the user model.