Wrapper class for `compound' operations, virtual instructions that
don't exist as byte code, but give a useful meaning. For example,
the (virtual) PUSH instruction takes an arbitray argument and produces the
appropiate code at dump time (ICONST, LDC, BIPUSH, ...). Also you can use the
SWITCH instruction as a useful template for either LOOKUPSWITCH or
TABLESWITCH.
The interface provides the possibilty for the user to write
`templates' or `macros' for such reuseable code patterns.