@CheckiO@Non-unique Elements

# Your optional code here
# You can import some modules or create additional functions


def checkio(data: list) -> list:
    # Your code here
    # It's main function. Don't remove this function
    # It's used for auto-testing and must return a result for check.
    length = len(data)
    data_list = []

    for i in range(length):
        if data.count(data[i]) > 1:
            data_list.append(data[i])

    # replace this for solution
    data = data_list
    return data

# Some hints
# You can use list.count(element) method for counting.
# Create new list with non-unique elements
# Loop over original list


if __name__ == "__main__":
    # These "asserts" using only for self-checking and not necessary for auto-testing
    assert list(checkio([1, 2, 3, 1, 3])) == [1, 3, 1, 3], "1st example"
    assert list(checkio([1, 2, 3, 4, 5])) == [], "2nd example"
    assert list(checkio([5, 5, 5, 5, 5])) == [5, 5, 5, 5, 5], "3rd example"
    assert list(checkio([10, 9, 10, 10, 9, 8])) == [10, 9, 10, 10, 9], "4th example"
    print("It is all good. Let's check it now")