Calculates and returns the element in a list that has repeated the most times in succession.

longest_repetition.py

def longest_repetition(list):
    best_length = 0
    best_element = None
    current_length = 0
    current_element = None
    for e in list:
        if e != current_element:
            current_element = e
            current_length = 1
        else:
            current_length += 1
        if current_length > best_length:
            best_length = current_length
            best_element = current_element
    return best_element
            
# print longest_repetition([1, 2, 2, 3, 3, 3, 2, 2, 1])
# 3