Repeat list

Your task is to implement a class that maintains a list of numbers and has an efficient method that reports if some number occurs more than once on the list.

In a file repeatlist.py, implement the class RepeatList with the following methods:

• append(number): add a number to the end of the list
• repeat(): return True if some number repeats on the list, otherwise return False

Both methods should work in $O(1)$ time

class RepeatList:
    def __init__(self):
        # TODO

    def append(self, number):
        # TODO

    def repeat(self):
        # TODO

if __name__ == "__main__":
    numbers = RepeatList()

    print(numbers.repeat()) # False

    numbers.append(1)
    numbers.append(2)
    numbers.append(3)
    print(numbers.repeat()) # False

    numbers.append(2)
    print(numbers.repeat()) # True

    numbers.append(5)
    print(numbers.repeat()) # True

Here the numbers $1$, $2$ and $3$ are first added to the list so that the list content is $[1,2,3]$ and there is no repeating number. Then the number $2$ is added to the list resulting in the content $[1,2,3,2]$ with a repeat of the number $2$. Finally, the number $5$ is added resulting in the content $[1,2,3,2,5]$ with the number $2$ still repeating.

You can test the efficiency of your solution with the following code. In this case too the code should finish almost immediately.

    numbers = RepeatList()
    total = 0
    for i in range(10**5):
        numbers.append(i * 999983 % 12345)
        if numbers.repeat():
            total += 1
    print(total) # 87655