from time import time 
t = time ()
abbreviations = ['cf.',' e.g.','ex.','etc.','fig.','i.e.','Mr.','vs.'] 
for i in range (1000000):
    for w in (' Mr.','Hat1','is','chasing', 'the','black', ' cat',  '.'):
        if w in abbreviations:
            #if w[-1] __ '.' and w in abbreviations: 
            pass
print ('total run time:')

print (time()-t)

t = time()
for i in range (1000000):
    for w in (' Mr.','Hat1','is','chasing', 'the','black', ' cat',  '.'):
        # if w in abbreviations:
        if w[-1] == '.' and w in abbreviations: 
            pass
print ('total run time:')

print (time()-t)

def fib ():
    a,b=0,1
    while True: 
        yield a 
        a, b =b, a+b
from itertools import islice 
print (list (islice (fib () , 5)))