docs: def prerequisites(self):
          """
          Iterates through the inputs of the pipelinen and determines the
          all prerequisite pipelines
          """
          # Loop through the inputs to the pipeline and add the instancemethods
          # for the pipelines to generate each of the processed inputs
          prereqs = defaultdict(set)
          for input in self.inputs:  # @ReservedAssignment
              spec = self._study.spec(input)
              # Could be an input to the study or optional acquired spec
              if spec.is_spec and spec.derived:
                  prereqs[spec.pipeline_getter].add(input.name)
          return prereqs