text: 'use strict';
  
  var Fabric = require('../');
  var fabric = new Fabric();
  
  fabric.use('OP_CHECKSIG', function (sig) {
    console.log('computing with OP_CHECKSIG:', sig);
    return true; // ;)
   
  });
  
  fabric.stack.push('<PUBLIC_KEY>');
  fabric.stack.push('<SIGNATURE>');
  fabric.stack.push('OP_CHECKSIG');
  
  fabric.compute();
  
  console.log('test:', fabric);
  