if isinstance(obj, int):

http://legacy.python.org/dev/peps/pep-0008/

 

Object type comparisons should always use isinstance() instead of comparing types directly.

Yes: if isinstance(obj, int):

No:  if type(obj) is type(1):

When checking if an object is a string, keep in mind that it might be a unicode string too!  In Python 2, str and unicode have a common base class, basestring, so you can do:

if isinstance(obj, basestring):

Note that in Python 3, unicode and basestring no longer exist (there is only str) and a bytes object is no longer a kind of string (it is a sequence of integers instead)