What does obj_now_BVHtree.overlap(obj1,obj2) return? I am using BVHtree.overlap in a script to calculate the overlap between 2 meshes. If there is no overlap this returns None. If there is an overlap a list is returned.
For example:

[(47491, 496), (47491, 498), (47310, 498), (47309, 498), (47036, 491), (47036, 498), (47581, 496), (47581, 489), (47580, 489), (47401, 496), (47035, 491), (47307, 489), (47216, 491), (47217, 491), (47032, 491), (47399, 489), (47308, 489), (46852, 491), (47031, 491), (47134, 489), (47134, 465), (46851, 491), (47030, 467), (47030, 465), (46934, 491), (46934, 467)]


What do the values in this list represent?
mathutils.bvhtree.BVHTree.overlap returns a list of unique tuples, where each tuple represents the overlap between two elements of the two trees. The first entry of each tuple is the index from one tree and the second entry is from the other tree.


  overlap(other_tree)
  
  Find overlapping indices between 2 trees.
  
  
  Parameters: other_tree(BVHTree) – Other tree to perform overlap test on. 
  Returns: Returns a list of unique index pairs, the first index referencing this tree, the second referencing the other_tree.
  Return type: list