# This function looks pretty innocent
def sum_of_values(d):
    return sum(d.values()) # Should run in O(len(d)), and we will only call with len(d) == 1



# Timing:
import timeit

def prepare_bad_example(N):
    d = {i: i for i in range(N)}
    for i in range(N-2, -1, -1):
        del d[i]
    return d

for N in [100000, 200000, 300000, 400000]:
    d = prepare_bad_example(N)
    print(N, timeit.timeit(f"sum_of_values(d)", number=10000, globals={"sum_of_values": sum_of_values, "d": d}))


# Output on my machine:
#
#
# 100000 0.3195033100055298
# 200000 0.6416430359968217
# 300000 1.0254385019943584
# 400000 1.3816945559956366