Matthew Barnett added the comment:
That behaviour has nothing to do with re.
This line:
samples = filter(lambda sample: not pttn.match(sample), data)
creates a generator that, when evaluated, will use the value of 'pttn' _at that
time_.
However, you then bind 'pttn' to something else.
New submission from ProFatXuanAll :
When I run the following code, I expected to get output result `['i am next
line with [unk]']`, but instead I get the original list in `data`.
Code snippet
```py
import re
data = [
'= hello =',
'i am next line with ',
]
pttn = re.compile(r'=.*=')
