refact(op, pipe): drop Plottable subclass already in Op

Author: ankostis

graphtik/op.py

@@ -214,7 +214,7 @@ def strip_sideffecteds(dep):
         return deps, deps
 
 
-class FunctionalOperation(Operation, Plottable):
+class FunctionalOperation(Operation):
     """
     An :term:`operation` performing a callable (ie a function, a method, a lambda).
 

graphtik/pipeline.py

@@ -114,7 +114,7 @@ def parent_wrapper(ren_args: RenArgs) -> str:
     return Network(*merge_set)
 
 
-class Pipeline(Operation, Plottable):
+class Pipeline(Operation):
     """
     An operation that can :term:`compute` a network-graph of operations.