docs: def reverse_cyk_transforms(root):
          # type: (Nonterminal) -> Nonterminal
          """
          Reverse transformation made to grammar before CYK.
          Performs following steps:
          - transform from chomsky normal form
          - restore unit rules
          - restore epsilon rules
          :param root: Root node of the parsed tree.
          :return: Restored parsed tree.
          """
          root = InverseContextFree.transform_from_chomsky_normal_form(root)
          root = InverseContextFree.unit_rules_restore(root)
          root = InverseContextFree.epsilon_rules_restore(root)
          return root