an empty list object therebut assigning an empty list to slice deletes the slice slice assignment expects another sequenceor you'll get type errorit inserts items inside the sequence assignednot the sequence itselfl [ , , , [ [ [ [] [ : [ [ del [ [ del [ : [ [ : traceback (innermost last)file ""line in typeerrorillegal argument type for built-in operation tuple assignment the values of and are swapped when tuples appear on the left and right of an assignment symbol (=)python assigns objects on the right to targets on the left according to their positions this is probably easiest to understand by noting that the targets on the left aren' real tupleeven though they look like onethey are simply set of independent assignment targets the items on the right are tuplewhich gets unpacked during the assignment (the tuple provides the temporary assignment needed to achieve the swap effect) 'spamy 'eggsxy yx 'eggsy 'spam dictionary keys any immutable object can be used as dictionary keyincluding integerstuplesstringsand so on this really is dictionaryeven though some of its keys look like integer offsets mixed-type keys work finetood { [ 'ad[ 'bd[( )'cd { ' ' ' '( )' ' dictionary indexing indexing nonexistent key ( [' ']raises an errorassigning to nonexistent key ( [' ']='spam'creates new dictionary entry on the other handout-of-bounds indexing for lists raises an error toobut so do out-of-bounds appendix dsolutions to end-of-part exercises