Find second largest number in an array

second_largest.py

def second_largest(given_list):
    len_of_list = len(given_list)
    if len_of_list == 1 or len_of_list == 0:
        return None
    
    if len_of_list == 2:
        if given_list[0] > given_list[1]:
            return given_list[1]
        else:
            return given_list[0]
        
    largest = given_list[0]
    second_largest = given_list[0]
    
    for item in given_list:
        if (item > largest):
            second_largest = largest
            largest = item
    
    return second_largest