Replacing specific words in a string (Python)

Question

I would like to replace words in a string sentence such as:

What $noun$ is $verb$?

What\'s the regular expression to replace the characters

Answer 1

In [1]: import re

In [2]: re.sub('\$noun\$', 'the heck', 'What $noun$ is $verb$?')
Out[2]: 'What the heck is $verb$?'