==================
Lambda Abstraction
==================

def foo := fun (A : ★) (x : A) : A => x;

----------

    (program
      (definition
        (identifier)
        (expr
          (app_term
            (labs
              (param_block
                (identifier)
                (expr
                  (app_term
                    (binex
                      (app
                        (term
                          (sort
                            (star))))))))
              (param_block
                (identifier)
                (expr
                  (app_term
                    (binex
                      (app
                        (term
                          (identifier)))))))
              (ascription
                (expr
                  (app_term
                    (binex
                      (app
                        (term
                          (identifier)))))))
              (expr
                (app_term
                  (binex
                    (app
                      (term
                        (identifier)))))))))))