# insert_pitfall.py

# insert_pitfall.py

# pitfall
a = [1,2,3,4]
a.insert(-1,5)
print (a)
# [1, 2, 3, 5, 4]

# solution
a = [1,2,3,4]
a.insert(len(a),5)
print (a)
# [1, 2, 3, 4, 5]