class_docstr: A tree-like structure to specify nested dependencies of key-value pairs
  In detail it maps dependencies of key requiring any number of key:value pairs
  
  Primarily useful for specifying nested dependencies of UI elements shown in Wave.
code: def __init__(self):
      self.dependencies: DefaultDict[
          str, List[Dependency]
      ] = defaultdict(list)
      self.triggers: Set[str] = set()
  
imports: from collections import defaultdict
  from dataclasses import dataclass
  from typing import DefaultDict, List, Optional, Set, Union
label_desc: Use image node_id 1 to create a new Nesting object  with example: obj = Nesting()