Get keys from template

Question

I would like to get a list of all possible keyword arguments a string template might use in a substitution.

Is there a way to do this other than re?

Answer 1

>>> import string
>>> get_keys = lambda s:[el.strip(string.punctuation) 
                         for el in s.split()if el.startswith('$')]
>>> get_keys("$one is a $lonely $number.")
['one', 'lonely', 'number']