let sum_three (a : real) (b : real) (c : real) : real =
  (* Add three numbers. *)
  basic.py.add (basic.py.add a b) c

let max_of_three (a : real) (b : real) (c : real) : real =
  (* Find maximum of three numbers. *)
  if a >=. b && a >=. c then
    a
  else if b >=. c then
    b
  else
    c

let circle_area (radius : real) : real =
  (* Calculate area of circle. *)
  let pi = 3.14159 in
  basic.py.multiply pi (math_ops.py.square radius)

let is_even (n : int) : bool =
  (* Check if integer is even. *)
  n mod 2 = 0
