const program = /* parse program ...*/;

const before: PreBlockHook = (blocktype, input, context) => { /* ... */ };
program.addHook('preBlock', before, { blocking: true });

const after: PostBlockHook = (blocktype, input, context, output) => { /* ... */ };
program.addHook('postBlock', after);  // Options can be omitted. Non-blocking is the default

const blockSpecificHook = (blocktype, input, context) => { /* ... */ };
myJayveeProgram.addHook('preBlock', blockSpecificHook, {
  blocktypes: ['BuiltinBlockType', 'MyCustomCompositeBlock'],
})

// interpret model ...