x = r("k")
y = l("ft")
z = x("t")
The answer is on the x(y(z("i36g9q4e")))
hint
= dl("u9j6")
The answer is
keyboard
because the functions are defined as
r() = right on the keyboard
l() = left on the keyboard
d() = down on the keyboard (u() presumably equals up but is not used)
thus we get
x = r('k') == l, so x is left
y = l('ft') == dr, so y is down then right
z = x('t') == r (see two lines up), so z is right
and finally the hint
is just down and left from u9j6 on the keyboard (ie u->h, 9->i, j->n, 6->t)
whence
z('i36g9q4e') -> o47h0w5r, y('o47h0w5r) -> lrunpstf, x('lrunpstf') -> keyboard!