How to set metadata on Canvas nodes through Python

Fabric_SetNodeMetaData.py

import FabricEngine.Core

import pymel.core as pm
from maya import cmds

# Create Maya Canvas Node and preset instance
nodeName = cmds.createNode('canvasNode', name='myGraph')
dummyVec3NodeName = cmds.FabricCanvasInstPreset(
                        mayaNode=nodeName,
                        execPath="",
                        presetPath="Fabric.Exts.Math.Constants.Vec3")

# Get the client, host, and graph binding
contextID = pm.FabricCanvasGetContextID()
options = {
    'contextID': contextID,
    'guarded': True
}

client = FabricEngine.Core.createClient(options)
dfgHost = client.getDFGHost()
opBindingID = cmds.FabricCanvasGetBindingID(node=nodeName) # Change node to the name of an existing canvasNode
opBinding = dfgHost.getBindingForID(opBindingID)
graphExec = opBinding.getExec()

# Get the Node
vec3NodeName = graphExec.getNodeName(0)
nodeType = graphExec.getNodeType(0)
nodeExec = graphExec.getSubExec(vec3NodeName)

# Set the Meta data
graphExec.setNodeMetadata(nodeExec.getExecPath(), 'curveIdx', 'blah', False, False)
print graphExec.getNodeMetadata(nodeExec.getExecPath(), 'curveIdx')