A formula reader

You will write the reader at the heart of a molar mass calculator. It turns a formula string into a dictionary of symbols and counts, then a second function opens one bracket.

The idea. re.findall(r"([A-Z][a-z]?)(\d*)", formula) gives pairs of a symbol and its digits; an empty count means one atom. A bracket with a number multiplies every atom inside it.

Your tasks.

1. In count_simple, return a dictionary of counts for a formula without brackets. Add up repeated symbols.
2. In molar_mass, return the molar mass using count_simple and atomic.
3. In count_bracket, handle a formula with one bracket, such as Al(OH)3.