Problem $6$

Extract all the identifiers. Identifiers are the names that programmers give to things, such as variables, function names, etc. In this programming language, they are composed of lowercase letters.

The identifiers in the program are: project, x$,$ y$,$ age, convert, temp, zip, foo, $...$

extract$($r$\text{'}\backslash$b$[$a$-$z$]+\backslash$b$\text{'},$ "program.txt$")$

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

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

in

$---->1$ extract$($r$\text{'}\backslash$b$[$a$-$z$]+\backslash$b$\text{'},$ "program.txt$")$

NameError: name 'extract' is not defined