Coercion rules

This section used to document the rules for coercion. As the language has evolved, the coercion rules have become hard to document precisely; documenting what one version of one particular implementation does is undesirable. Instead, here are some informal guidelines regarding coercion. In Python 3.0, coercion will not be supported.

• If the left operand of a % operator is a string or Unicode object, no coercion takes place and the string formatting operation is invoked instead.

• It is no longer recommended to define a coercion operation. Mixed-mode operations on types that don’t define coercion pass the original arguments to the operation.

• New-style classes (those derived from object) never invoke the __coerce__() method in response to a binary operator; the only time __coerce__() is invoked is when the built-in function coerce() is called.

• For most intents and purposes, an operator that returns ` NotImplemented` is treated the same as one that is not implemented at all.

• Below, __op__() and __rop__() are used to signify the generic method names corresponding to an operator; __iop__() is used for the corresponding in-place operator. For example, fo