use a set for nodes and always add each node when adding an edge
use a set for nodes and always add each node when adding an edge

mileswwatkins/pupa,rshorey/pupa,opencivicdata/pupa,mileswwatkins/pupa,datamade/pupa,influence-usa/pupa,rshorey/pupa,influence-usa/pupa,datamade/pupa,opencivicdata/pupa