The dataset file in assets$/$grades$.$txt contains a line separated list of people with their grade in a class. Create a regex to generate a list of just those students who received a B in the course.

import re

def grades$()$:

with open $("$assets$/$grades$.$txt$","$r$")$ as file:

grades $=$ file.read$()$

$$

# Regex pattern to match names followed by a $\text{'}$B$\text{'}$

pattern $=$ r$\text{'}\backslash$b$\backslash$w$+$B$\backslash$b$\text{'}$

#Find all matches and return a list of names

return re$.$findall$($pattern$,$ grades$)$

assert len$($grades$())==16$

$$

$---------------------------------------------------------------------------$

AssertionError Traceback $($most recent call last$)$

Cell In $[8],$ line $1$

$---->1$ assert len$($grades$())==16$

AssertionError: