Extract text

[Gribouillis]

You could use module itertools

import io
import itertools as itt

file = io.StringIO("""\
titi
titi
titi
yes
ok
ok
ok
no
totot
tototo
tot
""")

def takeuntil(pred, seq):
    for elem in seq:
        yield elem
        if pred(elem):
            return

seq = itt.dropwhile((lambda line: line != 'yes\n'), file)
seq = takeuntil((lambda line: line == 'no\n'), seq)

print(''.join(seq), end='')

Output:
yes
ok
ok
ok
no