Include a method that sets a specific value for a cursor (as well as min and max values) #2

Setting ranges for chromosome positions makes sense, however for other indexes where the user wants to get all matching rows (e.g. when REF=='A') things get more difficult. This is a particular problem as set_max is not inclusive, as such, to get all rows matching the last item (e.g. REF=='T'), we have to create a new key value that is definitely beyond it, then set minimum to T and maximum to our new 'maximal' key. When we have compound indexes, this can get complicated.

In fact, just making set_max inclusive would help a lot as it would allow this syntax to work as expected:

cursor.set_min(i.get_min())
cursor.set_max(i.get_max())

and a simple function for set_value would be something like:

def set_value(self, value):
      cursor.set_min(value)
      cursor.set_max(value)

Not sure what you'd do for binned indexes though...