hpricot：Hpricot::Container::Trav#get_elements_by_tag_name

everyday Ruby 
>> require "hpricot"
=> true
>> doc = Hpricot('<p>foo1</p><p>foo2</p>')
=> #<Hpricot::Doc {elem <p> "foo1" </p>} {elem <p> "foo2" </p>}>
>> doc.get_elements_by_tag_name('p')
=> #<Hpricot::Elements[{elem <p> "foo1" </p>}, {elem <p> "foo2" </p>}]>
>> doc = Hpricot('<p>foo1</p><p>foo2</p><b>foo3</b>')
=> #<Hpricot::Doc {elem <p> "foo1" </p>} {elem <p> "foo2" </p>} {elem <b> "foo3" </b>}>
>> doc.get_elements_by_tag_name('b')
=> #<Hpricot::Elements[{elem <b> "foo3" </b>}]>