...
byte[] data = ...;
LuaDataStream stream = new LuaDataStream(data);
LuaFileReader reader = new LuaFileReader(stream);

LuaFile file = reader.read();

...
LuaFunction main = file.getFunction();
Disassembler disasm = new Disassembler(main, System.out);
disasm.disassemble(); // print disassembly to main

// assuming that some function calls get set up in this sample
ClosureInstruction inst = main.getInstructions().get(0); 
// get the function referenced by this instruction
LuaFunction refFunction = inst.getProto();
...

// prepare a vm
VM vm = new VM();
vm.initialize();
// execute the main function
ExecutionContext result = vm.getHelper().invoke(main, vm.getGlobal());
Value val = results.get(0); // get R0

System.out.println(val.asString()); // print R0

// get the vm libraries
Libraries libs = vm.getLibraries();
Library base = libs.getTop(); // get the top library (the base library)
// choose a method (in this case 'print')
// then provide a new method to execute
base.set("print", (ctx) -> {
    System.out.println("Custom print call!");	
});

// or during/before execution access the global table and overwrite functions directly
Table global = vm.getGlobal();
// first define a new Closure
Closure customClosure = new Closure((ctx) -> {   
	System.out.println("Intercepted call!");
});
// wrap in ClosureValue
ClosureValue value = new ClosureValue(customClosure);        
// set new closure
global.set("customFunction", value);

vm.getInterpreter().install(Opcodes.MOVE, (Executor<LoadInstruction>) (insn, ctx) -> {
	System.out.println("Custom instructions");
});