hpricot：Hpricot::Container::Trav#classes

>> require "hpricot"
=> true
>> doc = Hpricot('<p>foo1</p><p>foo2</p>')
=> #<Hpricot::Doc {elem <p> "foo1" </p>} {elem <p> "foo2" </p>}>
>> doc.classes
NoMethodError: undefined method `get_attribute' for #<Hpricot::Doc {elem <p> "foo1" </p>} {elem <p> "foo2" </p>}>
	from /usr/local/ruby-1.8.7/lib/ruby/gems/1.8/gems/hpricot-0.8.2/lib/hpricot/traverse.rb:519:in `classes'
	from (irb):3
>> doc.at('p').classes
=> []
>> doc = Hpricot('<p class="foo">foo1</p><p>foo2</p>')
=> #<Hpricot::Doc {elem <p class="foo"> "foo1" </p>} {elem <p> "foo2" </p>}>
>> doc.classes
NoMethodError: undefined method `get_attribute' for #<Hpricot::Doc:0xb7981838>
	from /usr/local/ruby-1.8.7/lib/ruby/gems/1.8/gems/hpricot-0.8.2/lib/hpricot/traverse.rb:519:in `classes'
	from (irb):6
>> doc.at('p').classes
=> ["foo"]
>> doc = Hpricot('<p class="foo" class="bar">foo1</p><p>foo2</p>')
=> #<Hpricot::Doc {elem <p class="bar"> "foo1" </p>} {elem <p> "foo2" </p>}>
>> doc.at('p').classes
=> ["bar"]