deletions | additions       diff --git a/ball.md b/ball.md  deleted file mode 100644  index 22f5013..0000000  --- a/ball.md  +++ /dev/null 
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Image above reproduced from http://bl.ocks.org/mbostock/4062085   You should be able to use the left and right arrow keys to move the graph. You might have to click on the graph to gain focus.     Some online articles now let one rotate 3d figures. We can do better:  diff --git a/layout.md b/layout.md  index 568e199..ca8655e 100644  --- a/layout.md  +++ b/layout.md 
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figures/d3/index2.html  ball.md