pick 3 [3,2,5,3,(-5),4,3,2] == [3,3,3]
pick (-7) [3,2,5,3,(-5),4,3,2] == []
pick 2 [3,2,5,3,(-5),4,3,2] == [2,2]

pickAll [3,2,5] [3,2,5,3,(-5),4,3,2] == [3,2,5,3,3,2]
pickAll [(-7),5] [3,2,5,3,(-5),4,3,2] == [5]
pickAll [] [3,2,5,3,(-5),4,3,2] == []

variations 6 3 == 120
variations 6 9 == (-1)
variations 6 (-2) == (-1)

numberOfOcc 'a' "Banane" == 2
numberOfOcc 'b' "Banane" == 0
numberOfOcc 'B' "Banane" == 1

mostCommonSymbol "Bananen" == 'n'