title: Changing length of lines in a legend
body: <p>The following simple example...</p>
  
  <pre><code>plot(c(1,2),c(1,2),type="l")
  legend(1,1.5,legend="Test",lty=1,seg.len=2)
  </code></pre>
  
  <p>...produces the error </p>
  
  <blockquote>
    <p><code>Error in legend(1, 1.5, legend = "Test", lty = 1, seg.len = 2) : 
      unused argument (seg.len = 2)</code></p>
  </blockquote>
  
  <p>How should I use <code>seg.len</code> to get longer lines in legends?</p>