Python has a preferred way to document the purpose and
usage of your functions. If the first line of a function
body is a string constant, that string constant is saved
along with the function as the *documentation
string*. This string can be retrieved by
using an expression of the form

, where * f*.__doc__

`f`

is the function
name.
Here's an example of a function with a documentation string.

>>> def pythag(a, b): ... """Returns the hypotenuse of a right triangle with sides a and b. ... """ ... return (a*a + b*b)**0.5 ... >>> pythag(3,4) 5.0 >>> pythag(1,1) 1.4142135623730951 >>> print pythag.__doc__ Returns the hypotenuse of a right triangle with sides a and b. >>>