from typing import Dict


def divisor_sums_to(number: int) -> Dict[int, int]:
    """Returns a dictionary of numbers with the sum of their proper divisors, stopping before number

    Proper divisors of a number are the numbers less than that number that divide
    evenly into it e.g. the proper divisors of 10 are: 1, 2, 5 and the sum is 8.
    """
    divisor_sums = {n: 0 for n in range(0, number)}
    for n in range(1, number):
        for multiple_of_n in range(2 * n, number, n):
            divisor_sums[multiple_of_n] += n

    return divisor_sums