[] popular in python; ( ) is 99% for function call

Bracket [[[[ ]]]] is used for
– fast list initialization
– access a dict/tuple/str/list including ..
– slicing — for any sequence structure

Parenthesis (((( ))) is used mostly for function calls including pseudo-constructor calls like list() dict() str() int(). Other usages:

1. tuple initialization
2. !! Not needed for pair assignment