counting the number of occurrences in string

Question

A factory makes products using parts that are identified by letters A to L. Each product is made of at least 3 different parts, and is identified by a product code made up of letters identifying the parts. The letters in a product code is sorted alphabetically. E.g., a product with product code ABBBG is made up of 1 A, 3 B and 1 G parts.

(a) Write and develop a function getPartsInCode which has one string parameter: productCode.  For example, if product code is ABBBG, then the function returns 1A 3B 1G.

Note that the letters in the string parameter are in uppercase and are already sorted. You can use collections of only str type for function. This means collection types such as set, list, dict are not allowed.