- All the functions have the same calling sequence (arguments).
Every method must have the specified calling sequence, even
though it may not use some of the arguments.
- It is conventional to hyphenate the class name and selector
to make the name of the method; but not all of our method
names follow this pattern.
- In the send syntax, the object to which the message is sent
is always the first argument, and the selector (abstract function
name) is the second argument. The selector is quoted in our
implementation of message sending. Any other arguments follow
- The selector is not used as an argument of the method.