code: function Opcode(value, data) {
    if (!(this instanceof Opcode))
      return new Opcode(value, data);
  
    this.value = value || 0;
    this.data = data || null;
  }
docs: A simple struct which contains
  an opcode and pushdata buffer.
  Note: this should not be called directly.
  @alias module:script.Opcode
  @constructor
  @param {Number} value - Opcode.
  @param {Buffer?} data - Pushdata buffer.
  @property {Number} value
  @property {Buffer|null} data