Deleting from a list of mappings

Removing items from a list has an interesting consequence. Specifically, when item list[x] is removed, one of two other things will happen:

• Item list[x+1] takes the place of list[x]
• Item x+1 == len(list) takes the place of list[x] because x was the last index in the list

These are side-effects that happen in addition to removing an item. Because things can move around in a list, it makes deleting more than one item at a time challenging.

When the list contains items that have a definition for the __eq__() special method, then the list remove() method can remove each item. When the list items don't have a simple __eq__() test, then it becomes more challenging to remove multiple items from the list.

How can we delete multiple items from a list?

Getting ready

We'll work with a list-of-dict structure. In this case, we've got some data that includes a song name, the writers, and a duration. The data looks like this:

>>> source = [ 
...    {'title': 'Eruption...