def smallest_sums(partition:list, num_of_sums:int=1)->float:
    """
    Given a partition, return the sum of the smallest k parts (k = num_of_sums)
    >>> smallest_sums([[1,2],[3,4],[5,6]])
    3
    >>> smallest_sums([[1,2],[3,4],[5,6]], num_of_sums=2)
    10
    """
    sorted_sums = sorted([sum(part) for part in partition])
    return sum(sorted_sums[:num_of_sums])