code: func opcodeEqualVerify(op *parsedOpcode, vm *Engine) error {
  	err := opcodeEqual(op, vm)
  	if err == nil {
  		err = abstractVerify(op, vm, ErrEqualVerify)
  	}
  	return err
  }
docs: // opcodeEqualVerify is a combination of opcodeEqual and opcodeVerify.
  // Specifically, it removes the top 2 items of the data stack, compares them,
  // and pushes the result, encoded as a boolean, back to the stack.  Then, it
  // examines the top item on the data stack as a boolean value and verifies it
  // evaluates to true.  An error is returned if it does not.
  //
  // Stack transformation: [... x1 x2] -> [... bool] -> [...]