>>> from patients import filter_high_fever

>>> r = filter_high_fever('patients.txt', 'patout.txt', 37.1)
>>> with open('pat37.1.txt', 'r') as fref, open('patout.txt', 'r') as f:
... 	l = f.readline()
... 	lref = fref.readline()
... 	while l != '' and lref == l:
... 		l = f.readline()
... 		lref = fref.readline()
... 	iguals = lref == l == ''
>>> r == (9, 5) and iguals
True

>>> r = filter_high_fever('patients.txt', 'patout.txt', 38.5)
>>> with open('pat38.5.txt', 'r') as fref, open('patout.txt', 'r') as f:
... 	l = f.readline()
... 	lref = fref.readline()
... 	while l != '' and lref == l:
... 		l = f.readline()
... 		lref = fref.readline()
... 	iguals = lref == l == ''
>>> r == (9, 1) and iguals
True