(def
  (ident fn)
  (decl
    (list
      (param
        (ident x)
        (option)
        (option)
        (False))
      (param
        (ident y)
        (option)
        (option)
        (False))
      (param
        (ident z)
        (option)
        (option)
        (False)))
    (option))
  (list
    (assign
      (variable (ident q))
      (None))
    (assign
      (variable (ident q))
      (-
        (+
          (variable (ident x))
          (variable (ident y)))
        (apply
          (.
            (variable (ident z))
            (ident sigmoid))
          (list)
          (list))))
    (expression statement
      (apply
        (variable (ident print))
        (list (variable (ident q)))
        (list)))
    (assign
      (variable (ident w))
      (unary minus
        (variable (ident z))))
    (if
      (and
        (and
          (not (variable (ident x)))
          (not (variable (ident y))))
        (variable (ident z)))
      (list
        (assign
          (variable (ident m))
          (if
            (not (variable (ident z)))
            (variable (ident x))
            (variable (ident y)))))
      (list))
    (while
      (and
        (<
          (variable (ident x))
          (variable (ident y)))
        (>
          (variable (ident y))
          (variable (ident z))))
      (list
        (assign
          (variable (ident q))
          (variable (ident x)))))
    (assert
      (eq (const 1) (const 1))
      (option (string_literal hello)))
    (return (variable (ident x)))))