message: Add a few TODOs based on discussion with Andrew.
diff: @@ -124,6 +124,8 @@ class _WalkMode(Enum):
  REVERSE = 2
  +# TODO(mdan): Rename to DataFlowAnalyzer.
  +# TODO(mdan): Consider specializations that use gen/kill/transfer abstractions.
  class GraphVisitor(object):
  """Base class for a CFG visitors.
  @@ -161,6 +163,7 @@ class GraphVisitor(object):
  """
  raise NotImplementedError('Subclasses must implement this.')
  + # TODO(mdan): Rename to flow?
  def visit_node(self, node):
  """Visitor function.
  