mbostock/d3 — pull request #609 by kitmonisit (2012-04-04 14:50:47+00:00)
Title: Line defined usage example

I've added an example for the usage of the `.defined` function, based on the `line` example. For the `data` input, I've interspersed `null` values for `y`. When drawing ``s though, these `null`s don't come out very well, so I `filter`ed the data that comes in for the circle markers.