Why have a class with both a class variable and an instance variable of the same name?

Question

I've seen a few snippets of code in different languages where a class has a class variable, but then in the same class, there's also an instance variable of the same name. I'm trying to understand why we would do this? What would be the benefits of doing something like this:

class Paint:

    colour = 'red'

    def __init__(self, name, counter):        
        self.id = name        
        self.colour = colour

This is in Python and just an example. I'm trying to understand the benefits, and why someone would do this, in any programming language, but particularly C++, ruby, and python.

Answer 1

In Python that can be used for defaults.... for example:

class Foo:
    x = 1

a = Foo()
b = Foo()
print(a.x, b.x) # --> 1 1
a.x = 2
print(a.x, b.x) # --> 2 1