How can u invoke all the methods of a class at one go without explicit calling each?

# Lets define a class with some methods as:
class Nums:

    def __init__(self, n):
        self.val = n

    def multwo(self):
        self.val *= 2
    def addtwo(self):
        self.val += 2
    def devidetwo(self):
        self.val /= 2

# Lets create the instance of the class:
 f = Nums(2)

Now, call each and every methods as in dir(f) list. You should however, take care of methods taking arguments. Example, for init we need to pass args.

for m in dir(f):
    mymethod = getattr(f, m)
    if callable(mymethod):
        if 'init' not in str(mymethod):
            mymethod()
        else:
            pass

 print(f.val)  => It results 4. 

Wonder why ? 

To figure out, lets see in which order the methods within the class are invoked:
This is how the instance stores the methods and properties lists:
['__doc__', '__init__', '__module__', 'addtwo', 'devidetwo', 'multwo', 'val']
So, val = (2+2)/2*2 = 4