docs: function (db) {
          //create a table called state;
          return db
              .createTable("state", function () {
                  this.primaryKey("id");
                  this.name(String);
                  this.population("integer");
                  this.founded(Date);
                  this.climate(String);
                  this.description("text");
              })
              .chain(function () {
                  //create another table called capital
                  return db.createTable("capital", function () {
                      this.primaryKey("id");
                      this.population("integer");
                      this.name(String);
                      this.founded(Date);
                      this.foreignKey("stateId", "state", {key: "id", onDelete: "CASCADE"});
                  });
              });
      }