title: How to draw patches situated in crossroads?
body: <p>How can I draw in red the patches situated in crossroads (the roads are drawn in white) as in the figure below ?</p>
  
  <p>Here is my beginning of code: </p>
  
  <pre><code>ask patches with [ (pcolor = white) and (pxcor mod (nb-patch-length + 1) = 0 ) and (pycor mod (nb-patch-width + 1) = 0 ) ] [set pcolor red] 
  </code></pre>
  
  <p>Thanks in advance for your help.</p>
  
  <p><img src="https://i.stack.imgur.com/otBAr.png" alt="enter image description here"></p>