title: Extend line with given points
body: <p>I have a few lines plotted with points in a graph that look like the one in the image posted below:
  let's say for example that I have the coordinates for points A &amp; B, which I use to set the line. What I'd like to do is have the line go all the way from x=0 to x=100, adding the two missing &quot;x&quot; pieces.
  <img src="https://i.stack.imgur.com/QrNR3.png" alt="enter image description here" />
  I'm using <code>d3.svg.line()</code> to set the <code>.x</code> and <code>.y</code> accessor functions, and then a path to plot the line. Is there a function to add to the line or path generator that does what I'd like to obtain?
  Any hint is appreciated, thanks!</p>