Transform parsed tree to contain epsilon rules originally removed from the grammar.
    :param root: Root of the parsed tree.
    :return: Modified tree including epsilon rules.

def epsilon_rules_restore(root):
    # type: (Nonterminal) -> Nonterminal
    """
    Transform parsed tree to contain epsilon rules originally removed from the grammar.
    :param root: Root of the parsed tree.
    :return: Modified tree including epsilon rules.
    """
    items = Traversing.post_order(root)
    items = filter(lambda x: isinstance(x, EpsilonRemovedRule), items)
    for rule in items:
        # create original rule
        created_rule = rule.from_rule()  # type: Rule
        # attach parrents parents
        for s in rule.from_symbols:  # type: Nonterminal
            s._set_to_rule(created_rule)
            created_rule._from_symbols.append(s)
        # attach children up to replace index (that will contain epsilon)
        for i in range(rule.replace_index):
            ch = rule.to_symbols[i]  # type: Nonterminal
            ch._set_from_rule(created_rule)
            created_rule._to_symbols.append(ch)
        # add symbols originally rewrote to epsilon
        symb = _restore_tree_for(created_rule.right[rule.replace_index], rule.backtrack)  # type: Nonterminal
        created_rule._to_symbols.append(symb)
        symb._set_from_rule(created_rule)
        # attach rest of children
        for i in range(rule.replace_index, len(rule.to_symbols)):
            ch = rule.to_symbols[i]  # type: Nonterminal
            ch._set_from_rule(created_rule)
            created_rule._to_symbols.append(ch)
    return root