The decorator pattern, also known as the wrapper pattern, is when you wrap an object within another object, thus providing a means of enhancing or overriding certain behavior. The wrapper object will delegate any incoming method calls to the original object, unless it defines a new method to enhance or replace the original object’s behavior. By using the decorator pattern, you can dynamically create as many decorated objects as you want, each enhancing the behavior of the original object in a unique way — and all without mutating the original object. In this manner, you can effectively add, remove, or extend behaviors at runtime.

Note that greet_bob(say_hello) refers to two functions, but in different ways: greet_bob() and say_hello. The say_hello function is named without parentheses. This means that only a reference to the function is passed. The function is not executed. The greet_bob() function, on the other hand, is written with parentheses, so it will be called as usual.
In this snippet we have a class hierarchy with a SimpleMessage at the top. The SimpleMessage class has a constructor that accepts a content string as well as two methods: GetMessage; and, PrintMessage. Down the hierarchy we have three subclasses: ExcitedMessage; QuizzicalMessage; and, ExcitedAndQuizzicalMessage. The only difference in the subclasses is that they override the SimpleMessage constructor to change the content string and append various exclamations. When we instantiate various message objects, using the same content string, and iterate over them, each has their own unique output.
After 2.4a2 was released, in response to community reaction, Guido stated that he'd re-examine a community proposal, if the community could come up with a community consensus, a decent proposal, and an implementation. After an amazing number of posts, collecting a vast number of alternatives in the Python wiki [18], a community consensus emerged (below). Guido subsequently rejected [22] this alternate form, but added:
Pastel is a painting medium in the form of a stick, consisting of pure powdered pigment and a binder.[19] The pigments used in pastels are the same as those used to produce all colored art media, including oil paints; the binder is of a neutral hue and low saturation. The color effect of pastels is closer to the natural dry pigments than that of any other process.[20] Because the surface of a pastel painting is fragile and easily smudged, its preservation requires protective measures such as framing under glass; it may also be sprayed with a fixative. Nonetheless, when made with permanent pigments and properly cared for, a pastel painting may endure unchanged for centuries. Pastels are not susceptible, as are paintings made with a fluid medium, to the cracking and discoloration that result from changes in the color, opacity, or dimensions of the medium as it dries.
Painting is an important form in the visual arts, bringing in elements such as drawing, gesture (as in gestural painting), composition, narration (as in narrative art), or abstraction (as in abstract art).[2] Paintings can be naturalistic and representational (as in a still life or landscape painting), photographic, abstract, narrative, symbolistic (as in Symbolist art), emotive (as in Expressionism), or political in nature (as in Artivism).