f(g(h(x)))

F‿G‿H ← ⟨-, 1⊸+, 2⊸×⟩

# very similar to the math
(F(G(H))) 5

# 2-trains are already f(g(x))
# composes the three functions into two 2-trains
(F(G H)) 5

# Nothing can break trains up into 2-trains as well
!¯11=(F·G H) 5
! 11=(F·F·G H) 5
(F·F·F·G H) 5