What is this python syntax trying to do? -

i'm wondering trying happen in following line. forgive me i'm new python syntax, help!

handlers[type(dbw_msg)](dbw_msg) 

where handlers = secondary: self.secondary_manage.handle.message

and dbw_msg = py_from_can(can_msg)

where py_from can defined as

def py_from_can(can_msg): try:     if can_msg.id in py_can_types:         return py_can_types[can_msg.id].py_from_can(can_msg) except notimplementederror:     pass return none 

so, without other context, can is:

handlers[type(dbw_msg)](dbw_msg) 

handlers gets subscripted (i.e. square-brackets) type(db_msg). can assume sort of mapping (a dict) keys type objects.

finally, value returned subcription operation get's called, i.e. () parens. so, handlers mapping type objects callable (e.g. functions).

so, example:

>>> handlers = {int: lambda x: x**2, str: str.upper}     >>> = 8 >>> b = 'foo' >>> handlers[type(a)](a) 64 >>> handlers[type(b)](b) 'foo' 

note, str.upper merely .upper method normal strings, i.e.:

>>> "baz".upper() # note call! 'baz' 

is same as:

>>> str.upper("baz") 'baz' 

and lambda merely way write anonymous functions. equivalent to:

def square(x):     return x**2