Add a node by form name and value with optional props.

        Args:
            name (str): The form of node to add.
            valu (obj): The value for the node.
            props (dict): Optional secondary properties for the node.

async def addNode(self, name, valu, props=None):
        '''
        Add a node by form name and value with optional props.

        Args:
            name (str): The form of node to add.
            valu (obj): The value for the node.
            props (dict): Optional secondary properties for the node.
        '''

        try:

            fnib = self._getNodeFnib(name, valu)
            retn = await self._addNodeFnib(fnib, props=props)
            return retn

        except asyncio.CancelledError:
            raise

        except Exception:

            mesg = f'Error adding node: {name} {valu!r} {props!r}'
            logger.exception(mesg)
            if self.strict:
                raise

            return None