def flatten_list(list1):
    if flat(list1):
        return list1

    result = []
    for element in list1:
        if (type(element) is list):
            flattened_element = flatten_list(element)
            result = result + flattened_element
        else:
            result = result + [element]

    return result

"""
returns true if the list is flat (contains no lists as elements)
"""
def flat(list1):
    for element in list1:
        if type(element) is list:
            return False

    return True


def flatten_list2(object1):
    if not(type(object1) is list):
        return [object1]

    result = []
    for element in object1:
        flattened_element = flatten_list2(element)
        result = result + flattened_element
            
    return result


def flatten_list3(list1):
    current_list = list1
    
    while(not(flat(current_list))):
        new_list = []
        for element in current_list:
            if type(element) is list:
                new_list = new_list + element
            else:
                new_list = new_list + [element]

        current_list = new_list

    return current_list