Given a nested dictionary, print all leaf elements (values that are not dictionaries).

A leaf element is any value that is not a dictionary. You can collect them with a simple recursive function: iterate over each key, if the value is a dict, recurse; otherwise, append the value to a list. For example, with the dictionary {'a': 1, 'b': {'c': 2, 'd': {'e': 3}}, 'f': {'g': 4}}, the function will return [1, 2, 3, 4]. The algorithm visits each node once, giving O(n) time complexity, and uses O(h) stack space, where h is the maximum depth of nesting.