Create a Python program to sort a list of tuples based on the second element in each tuple.
[(1, 2), (4, 1), (9, 10), (13, -3)]
def sort_tuples(a):
    return sorted(a, key = lambda x: x[1])

a = [(1, 2), (4, 1), (9, 10), (13, -3)]
print(sort_tuples(a))

# Output: [(13, -3), (4, 1), (1, 2), (9, 10)]