!!
%+ sub %+ mul 3 3 4

the same nesting written tall.

follow the indentation inward to see the inner call.

glossary

%+ calls a gate that takes two arguments.

%+(add 2 3) is 5.

irregular forms:

(gate a b) is %+(gate a b)

sub subtracts the second atom from the first.

(sub 9 4) is 5.

mul multiplies two atoms.

(mul 3 4) is 12.