Conditionals and Loops

Conditions and invariants are always expected to be tuples of length 1.

if condition then consequence end
Returns the value of consequence if the value of condition is not 0, 0 otherwise.
if condition then consequence else alternative end
Returns the value of consequence if the value of condition is not 0, otherwise the value of alternative.
while invariant do body end
While invariant is not 0, executes body, then returns 0.
do body while invariant end
Executes body until invariant is not equal 0, then returns 0.