A plotly.js sankey trace auto-detected by MAIDR. Following a
ribbon is the primary move and it is on the keys that already exist:
right follows the largest flow out of the current node, left follows the
largest flow in, and up and down walk the other nodes stacked in the same
column. Plotly names the ends of each flow by index; MAIDR resolves them
back to the node labels, because "34 from Coal to Electricity" is the
reading and "34 from 0 to 1" is not.