more_collections :: HashMap4 :: has
k1, k2, k3, k4
# Is there a value at `k1, k2, k3, k4`? fun has(k1: K1, k2: K2, k3: K3, k4: K4): Bool do if not level1.keys.has(k1) then return false return level1[k1].has(k2, k3, k4) end