使用ruby Nokogiri，我有一个Nokogiri::XML::Node对象（ConstituencyXMLNode继承自Nokogiri::XML::Node），它是一个树对象，如下所示：

#(ConstituencyXMLNode:0xc3c8 {
  name = "PP",
  children = [
    #(ConstituencyXMLNode:0xc3dc { name = "IN", children = [ #(Text "out")] }),
    #(ConstituencyXMLNode:0xc3f0 {
      name = "PP",
      children = [
        #(ConstituencyXMLNode:0xc404 { name = "IN", children = [ #(Text "of")] }),
        #(ConstituencyXMLNode:0xc418 {
          name = "NP",
          children = [
            #(ConstituencyXMLNode:0xc42c { name = "JJ", children = [ #(Text "non-living")] }),
            #(ConstituencyXMLNode:0xc440 { name = "NNS", children = [ #(Text "resources")] })]
          })]
      })]
  })

我们称之为pp_leaf
我想比较一下这个节点的部分是否包含在另一个部分Nokogiri：：XML：：Node中：

#(ConstituencyXMLNode:0xc3f0 {
  name = "PP",
  children = [
    #(ConstituencyXMLNode:0xc404 { name = "IN", children = [ #(Text "of")] }),
    #(ConstituencyXMLNode:0xc418 {
      name = "NP",
      children = [
        #(ConstituencyXMLNode:0xc42c { name = "JJ", children = [ #(Text "non-living")] }),
        #(ConstituencyXMLNode:0xc440 { name = "NNS", children = [ #(Text "resources")] })]
      })]
  })

我们将这个节点称为current_leaf。
看起来Nokogiri::XML::NodeSet有我正在寻找的比较工具，但我不确定如何将Nokogiri::XML::Node转换为Nokogiri::XML::NodeSet。如果一个集合包含另一个集合，Nokogiri::XML::Node上的运算符似乎都没有我需要匹配的比较运算符。
有什么想法吗