gremlin> g.mergeE([(T.id):'11']).option(onMatch, ["weight":0.4], set)
==>e[11][4-created->3]
gremlin> g.E().valueMap(true)
==>[id:11,label:created,weight:[set, 0.4]]
==>[id:12,label:created,weight:0.2]
==>[id:7,label:knows,weight:0.5]
==>[id:8,label:knows,weight:1.0]
==>[id:9,label:created,weight:0.4]
==>[id:10,label:created,weight:1.0]
gremlin> g.mergeE([(T.id):'11']).option(onMatch, ["weight":0.75], set)
==>e[11][4-created->3]
gremlin> g.E().valueMap(true)
==>[id:11,label:created,weight:[set, 0.75]]
==>[id:12,label:created,weight:0.2]
==>[id:7,label:knows,weight:0.5]
==>[id:8,label:knows,weight:1.0]
==>[id:9,label:created,weight:0.4]
==>[id:10,label:created,weight:1.0]