add three nodes A-C
add associated data to node A: color with value blue
add associated color data to nodes B and C: make them green and blue, respectively
define a style foo that specifies a node shape of rectangle
apply the style foo to exactly those nodes that have color data equal to blue
add associated count data of 3 for node A and 2 for node B
set the node size for all nodes to be the count data or 1 if it has no count data
set each node's line color to its color data