take(0, L) = [ ]
Example: take(0, [2,4,6]) = [ ].
take(n, [ ]) = [ ]
Example: take(4, [ ]) = [ ].
take(n, L) = [head(L)] ++ take(n-1, tail(L))
Example: take(3, [2,4,6,8,10]) = [2] ++ take(2, [4,6,8,10]) = [2] ++ [4,6] = [2,4,6].