A helper class for code generation. Items are objects
that stand for addressable entities in the bytecode. Each item
supports a fixed protocol for loading the item on the stack, storing
into it, converting it into a jump condition, and several others.
There are many individual forms of items, such as local, static,
indexed, or instance variables, values on the top of stack, the
special values this or super, etc. Individual items are represented as
inner classes in class Items.
This is NOT part of any supported API.
If you write code that depends on this, you do so at your own risk.
This code and its internal interfaces are subject to change or
deletion without notice.
