QuantumGraphNodes represents a bunch of nodes in an quantum graph.
The node in quantum graph is represented by the `PipelineTask` and a
single `Quantum` instance. One possible representation of the graph is
just a list of nodes without edges (edges can be deduced from nodes'
quantum inputs and outputs if needed). That representation can be reduced
to the list of PipelineTasks and the corresponding list of Quanta.
This class defines this reduced representation.
Different frameworks may use different graph representation, this
representation was based mostly on requirements of command-line
executor which does not need explicit edges information.
Attributes
----------
taskDef : :py:class:`TaskDef`
Task defintion for this set of nodes.
quanta : `list` of :py:class:`lsst.daf.butler.Quantum`
List of quanta corresponding to the task.
Definition at line 51 of file graph.py.