<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _get_covered_keys_and_masks(merge, aliases):
 """Get keys and masks which would be covered by the entry resulting from the merge. Parameters Map of key-mask pairs to the sets of key-mask pairs that they actually represent. Yields ------ (key, mask) Pairs of keys and masks which would be covered if the given `merge` were to be applied to the routing table. """

    # For every entry in the table below the insertion index see which keys
    # and masks would overlap with the key and mask of the merged entry.
    for entry in merge.routing_table[merge.insertion_index:]:
        key_mask = (entry.key, entry.mask)
        keys_masks = aliases.get(key_mask, [key_mask])

        for key, mask in keys_masks:
            if intersect(merge.key, merge.mask, key, mask):
                yield key, mask