Appends a sound at the end of another sound.
s2 are sounds with the same bit depth and sample frequency, then
AppendSound(s1, s2) returns the sound with this bit depth and sample frequency that contains
s2 after each other.
S ≔ compute(SineTone(100⋅n, 0.2, 0.2), n, 1, 10); accumulate(S, SineTone(50, 0.2, 0.2), AppendSound)