Creates a bucket info for the currently empty bucket specified by bucket_index, sets the length to 1; increases the number of non-empty buckets by 1.
index of the bucket into which the first element has been put
In: The bucket is expected to be currently empty.
See Implementation
Creates a bucket info for the currently empty bucket specified by bucket_index, sets the length to 1; increases the number of non-empty buckets by 1.