code: public Part createPart(String partLabel) {
  	  Part part;
  	  if ((part = getPart(partLabel)) != null)
  		  return part;
  	  // check should be requiered to see if the label is not 
  	  // empty or blank character because the blank character is
  	  // used as flag for the default part.
  	  part = new Part(this, partLabel);
  	  if (m_parts==null) m_parts = new ArrayList();
  	  m_parts.add(part);
  	  return part;
    }
docs: Creates a new part in this tune if doesn't exist and returns it.
  @param partLabel The label defining this new tune part.
  @return The new part properly labeled.