Mubashir needs your help in a simple task of multiplication of elements in a given list.
Create a function which takes a list of integers lst and a positive integer k and returns the minimum and maximum possible product of k elements taken from the list. If enough elements are not available in the list, return None.
product_pair([1, -2, -3, 4, 6, 7], 1) ➞ (-3, 7)
product_pair([1, -2, -3, 4, 6, 7], 2) ➞ (-21, 42)
# -3*7, 6*7
product_pair([1, -2, -3, 4, 6, 7], 3) ➞ (-126, 168)
# -3*6*7, 4*6*7
product_pair([1, -2, -3, 4, 6, 7], 7) ➞ None
# There are only 6 elements in the list
N/A