how to do a simple benchmarking with timeit

benchmark.py

def a():
    x = 'XBmYxJY6pP64vV4Km7pnxuC854XweJ6TkuuBvd5SDd64HZcfM5wZxH5GPX4n'
    x = x[::-1]


def b():
    x = 'v3xy4FMR25vmy8FznB2RzE3b649rS7v9ez5Z4yTAdye6nWw5t928ac7dP3S2'
    x = x[::-1]


def c():
    x = 'K5uhJpUC8Xpw7Z4Qbb5G2PM687qRJbwc6v94kN8C2c5eR3Mg7t23MkCBVfVm'
    x = x[::-1]


def d():
    a()
    b()
    c()

# python -m timeit -s 'import tmp3' 'tmp3.a()' 'tmp3.b()' 'tmp3.c()'
# python -m timeit -s 'import tmp3' 'tmp3.d()'
# python -m timeit -n 10000000 -r 5 -s 'import tmp3' 'tmp3.a()' 'tmp3.b()' 'tmp3.c()'