-----Description-----
This task requires writing a Lean 4 method that finds the majority element in a list of natural numbers. The majority element is defined as the element that appears more than ⌊n / 2⌋ times in the list, where n is the total number of elements.

You may assume that the input list always contains a majority element.

-----Input-----
The input consists of one list:
xs: A list of natural numbers (List Nat), where a majority element is guaranteed to exist.

-----Output-----
The output is a natural number:
Returns the element that appears more than half the time in the input list.

