() .
Are all operators, what they do is defined by the values that they are used on.
 makes use of
__setitem__ depending on how it's used,
= is assignment, what exactly that means varies a lot based on what's on the left side of it.
: is not an operator, it's just used in various places in the syntax
More about those special names here: https://docs.python.org/2/reference/datamodel.html
Generally those names are used to implement various language features and aren't meant to be used directly. For example, a value that can be iterated through in a for-loop will need to have an
Those do not exist in Python, statements are language constructs, they can't be called. Expressions evaluate to values, and you can use operators with values.