title: LINQ returning variable number of outputs for each input (point list to line list)
body: <p>I have a list like (1,5,8,9) and I want to return a list like (10,50,50,80,80,90).</p>
  
  <p>Is LINQ suitable for such a transformation?</p>
  
  <p>The actual application is given a list of objects with calculable (x,y) coordinate and returning list of line segments between the objects.</p>