List attributes of an object [duplicate]

Is there a way to grab a list of attributes that exist on instances of a class?

class new_class():
    def __init__(self, number):
        self.multi = int(number) * 2
        self.str = str(number)

a = new_class(2)
print(', '.join(a.SOMETHING))

The desired result is that "multi, str" will be output. I want this to see the current attributes from various parts of a script.

>>> class new_class():
...   def __init__(self, number):
...     self.multi = int(number) * 2
...     self.str = str(number)
... 
>>> a = new_class(2)
>>> a.__dict__
{'multi': 4, 'str': '2'}
>>> a.__dict__.keys()
dict_keys(['multi', 'str'])

You may also find pprint helpful.

dir(instance)
# or (same value)
instance.__dir__()
# or
instance.__dict__

Then you can test what type is with type() or if is a method with callable().