For undirected graphs, the 'epsilon' attribute decides how long the graph solver tries before finding a graph layout. Lower numbers allow the solver to fun longer and potentially give a better layout. Larger values can decrease the running time but with a reduction in layout quality. The default is 0.1. The value should be a hash reference containing the corresponding key-value pairs.
All nodes have a name attached which uniquely represents that node.
If not specified, the 'fillcolor' when the 'style' is 'filled' defaults to be the same as the outline color style sets the style of the node. If you wish to add an anonymous node, that is a node for which you do not wish to generate a name, you may use the following form, where the GraphViz module generates a name and returns it for you. An empty string means not clustered. Nodes with the same rank value are ranked together. This is implemented by passing an array reference as the label, and the parts are displayed as a label.