root@benchmarks:~# tail -n +1 *.py
==> afnp_exist.py <==
import timeit

def lookup(d, k):
    try:
        return d[k]
    except KeyError:
        pass


setup = """
from __main__ import lookup 
d = {'a': 1} 
k = 'a'
"""

N = 100000000
print(timeit.timeit("lookup(d, k)", setup=setup, number=N))

==> afnp_no_exist.py <==
import timeit

def lookup(d, k):
    try:
        return d[k]
    except KeyError:
        pass


setup = """
from __main__ import lookup 
d = {'a': 1} 
k = 'b'
"""

N = 100000000
print(timeit.timeit("lookup(d, k)", setup=setup, number=N))


==> lbyl_exist.py <==
import timeit

def lookup(d, k):
    if k in d:
        return d[k]


setup = """
from __main__ import lookup 
d = {'a': 1} 
k = 'a'
"""

N = 100000000
print(timeit.timeit("lookup(d, k)", setup=setup, number=N))


==> lbyl_no_exist.py <==
import timeit

def lookup(d, k):
    if k in d:
        return d[k]


setup = """
from __main__ import lookup 
d = {'a': 1} 
k = 'b'
"""

N = 100000000
print(timeit.timeit("lookup(d, k)", setup=setup, number=N))