class_docstr: A tree choice chooses one path to a leaf in a tree
  
  Trees are represented as collections of two-tuples. The first element is
  the name of the node and the second is either None if a leaf or
  a sub-collection of two-tuples. For instance:
  (("Foo", (("1", None),("2", None))), ("Bar", None))
  is a tree for selecting ("Foo", "1"), ("Foo", "2") or ("Bar",).
  
  A good UI choice would be a hierarchical menu.
code: def test_valid(self, pipeline):
      self.get_selected_leaf()
  
file_path: CellProfiler/src/subpackages/core/cellprofiler_core/setting/_tree_choice.py
imports: import re
  from ._setting import Setting
  from ._validation_error import ValidationError
label_desc: Use image node_id 8 for calling the TreeChoice obj's underlying member method code with example usage: obj.test_valid(pipeline) without return types