De?nition

A method de?nition has the abstract form:

def (, ..., ):

...

There are essentially three parts:

• is a name for the procedure, with the similar limitation as a variable name;

• , ..., is a list of formal arguments, which will given for the data elements on which this procedure will operate; and

• , ..., , known as the body of the method, is a list of Python statements (right now, we know about assignment expression, print instruction.)

When we compute a procedure de?nition in an environment, E, Python does have two things:

1. Makes a procedure object19  that contains the formal parameters, the body of the function, and a pointer to E; and then

2. Binds the name  to have this procedure as its value.

Here is a program of an environment after we have calculated

Note how  the construct to which  square points  is a procedure body, with  a number of formal  parameters,  a object, and a pointer to its environment.