The function can be implemented using a lambda function. Given the list containing strings starting with a lowecase or a uppercase letter. The sum of the lengths of each string starting with an uppercase letter can be determined as follows: First remove all the strings that start with a lowercase letter using the filter function. The filtering condition can be dynamically created using a lambda function which iterates over the strings and checks whether a string starts with an uppercase or a lowercase letter keeping only the strings starting with an uppercase letter. The filter function returns an iterator with the elements that pass the filtering condition. To convert it to a list, you can use the list(...) constructor. Finally, join each string of the filtered list and return its length to count the sum of the lengths of each string starting with an uppercase letter.