In Python, everything is an object

http://www.cnblogs.com/xybaby/p/6270551.html

https://docs.python.org/2/howto/descriptor.html

(ref: https://stackoverflow.com/questions/865911/is-everything-an-object-in-python-like-ruby)

DiveIntoPython - Everything Is an Object

Everything in Python is an object, and almost everything has attributes and methods. All functions have a built-in attribute __doc__, which returns the doc string defined in the function's source code. The sys module is an object which has (among other things) an attribute called path. And so forth.

Still, this begs the question. What is an object? Different programming languages define “object” in different ways. In some, it means that all objects must have attributes and methods; in others, it means that all objects are subclassable. In Python, the definition is looser; some objects have neither attributes nor methods (more on this in Chapter 3), and not all objects are subclassable (more on this in Chapter 5). But everything is an object in the sense that it can be assigned to a variable or passed as an argument to a function (more in this in Chapter 4).