for line in f
reads all file to a memory, and that can be a problem.
My offer is to change the original source by replacing stripping and checking for empty line. Because if it is not last line - You will receive at least newline character in it ('\n'). And '.strip()' removes it. But in last line of a file You will receive truely empty line, without any characters. So the following loop will not give You false EOF, and You do not waste a memory:
with open("blablabla.txt", "r") as fl_in:
while True:
line = fl_in.readline()
if not line:
break
line = line.strip()
# do what You want