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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_pipeline_names():
 """Returns the class paths of all Pipelines defined in alphabetical order."""

  class_path_set = set()
  for cls in _PipelineMeta._all_classes:
      if cls.class_path is not None:
        class_path_set.add(cls.class_path)
  return sorted(class_path_set)