docs: def global_symbols_in_children(self):
          """
          This is based on all children referenced symbols that have not
          been declared.
  
          The intended use case is to ban the symbols from being used as
          remapped symbol values.
          """
  
          result = set()
          for child in self.children:
              result |= (
                  child.global_symbols |
                  child.global_symbols_in_children)
          return result