title: Create a custom block with no input or output ports
body: <p>I would like to create a custom block in GNU Radio which takes two parameters and has <strong>no input or output</strong> ports.</p>
  
  <p>I have read about the block types on GNU Radio but I'm unsure on which will be best suited for my scenario.</p>
  
  <p>The purpose of the block is to add images to the <code>Top Block</code> with respect to the data received in it's parameter.</p>
  
  <p>I would like to know what <strong>type of block</strong> I should use for this scenario.</p>