How do I invoke a for loop in a method with argument "self"

    def commandType(self):
    '''P.commandType() -> str
    '''
    for i in self:
        .........

I want to write a for loop such that I am able to loop through the Contents of "P" object. What is the best way to call it in python. PS: ignore the PASS command.

Which one For i in self: or for i in P: work?