title: d3.js alternative to axis.tickSubdivide?
body: <p>I want to draw subtick in the axis in D3.
  But it seems impossible in the latest D3.</p>
  
  <p>There was axis.tickSubdivide() function to draw the subtick, but I think that is deprecated.(<a href="https://github.com/mbostock/d3/commit/bd0ce6cab8a2b0d2aaffc7ce21a873fc514eb8ed" rel="noreferrer">https://github.com/mbostock/d3/commit/bd0ce6cab8a2b0d2aaffc7ce21a873fc514eb8ed</a>)</p>
  
  <p>And axis.tickSubdivide() is not on the API(<a href="https://github.com/mbostock/d3/wiki/API-Reference" rel="noreferrer">https://github.com/mbostock/d3/wiki/API-Reference</a>) any more.</p>
  
  <p>I tried with axis.innerTickSize but it didn't work.</p>
  
  <p>Is there any way to draw subtick on the axis at my disposal?</p>
  
  <p>I found an example(<a href="http://bl.ocks.org/GerHobbelt/3605124" rel="noreferrer">http://bl.ocks.org/GerHobbelt/3605124</a>) which used axis.tickSubdivide(), but I can't figure out how it can work even when embedded d3.v3.min.js says "n.tickSubdivide=function(){return arguments.length&amp;&amp;n}", which doesn't do anything and just return the axis.</p>