deletions | additions       diff --git a/intro.md b/intro.md  index d8e972c..0971943 100644  --- a/intro.md  +++ b/intro.md 
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####Image ##Image  reproduced from http://bl.ocks.org/mbostock/4062085 ####You 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.