apply method
Partially applies the first argument to the function without currying it.
Essentially acts as a shortcut of currying a function, applying the first argument and immediately uncurrying it back.
Implementation
F6<B, C, D, E, F, G, T> apply(A a) =>
(b, c, d, e, f, g) => this(a, b, c, d, e, f, g);