Almost works in the wiki. Nodes get created but edges/connectors are lost.

custom_mark10 digraph G { size ="4,4"; main [shape=box]; main -- parse [weight=8]; parse -> execute; main -> init [style=dotted]; main -> cleanup; execute -> { make_string; printf}; init -> make_string; edge [color=red]; main -> printf [style=bold,label="100 times"]; make_string [label="make a string"]; node [shape=box,style=filled,color=".7 .3 1.0"]; execute -> compare; } custom_mark10

Works OK. Use something like https://www.urlencoder.org/ to encode and/or de-encode.