Could someone write this program in python

def last index(xs, key): Search through the list xs for value key return the non-negative index corresponding to the last occurrence of key. If it's not found, return None. Remember: the rightmost match should be reported when multiple matches are present. Assumption: xs is a list; xs could be empty. Restriction: You can NOT call.index() or .reverse() - just loop through manually and seek the key. Do NOT modify the incoming list xs. Examples: o o o last-index( [5,10,15,20,25], 15) last-index( [3,4,5,6,4,4,5], 4) last-index( [100,105,110], 234) 5 None # 4 is at indexes 1,4,5