class Parser::AST::Node

def count_nodes_of_type(*types)
  count = 0
  recursive_children do |child|
    count += 1 if types.include?(child.type)
  end
  count
end

def recursive_children
  children.each do |child|
    next unless child.is_a?(Parser::AST::Node)
    yield child
    child.recursive_children { |grand_child| yield grand_child }
  end
end