arams'>params</span><span class='lbracket'>[</span><span class='symbol'>:extension</span><span class='rbracket'>]</span><span class='period'>.</span><span class='id identifier rubyid_to_sym'>to_sym</span>
  <span class='id identifier rubyid_raise'>raise</span> <span class='const'>PackageNotFound</span> <span class='kw'>unless</span> <span class='lparen'>(</span><span class='const'>VALID_FORMATS</span> <span class='op'>+</span> <span class='lbracket'>[</span><span class='const'>Jammit</span><span class='peri