title: Vertical line with every quotation
body: <p>I often want to tell some comments inside of the text, which aren't so closely related to the discussed topic. Usually for this purpose I use the <code>quotation</code> environment, because of its large indent on the left. The comment can be large, it can include formulas, code listings, nested quotations, and so on.</p>
  
  <p>How can I make <code>quotation</code> environment to draw a long vertical line on the left of all its content? You can often find this style on the Web with the actual quotes.</p>
  
  <p>Google has found one solution:</p>
  
  <pre class="lang-tex prettyprint-override"><code>\begin{flushleft}
  \hbox{%
  \vrule\hspace{.5em}\parbox{.9\textwidth}%
  {Lorem ipsum dolor sit amet, consectetur adipiscing elit. Morbi id hendrerit 
  nunc. Sed scelerisque lacus vitae erat eleifend eleifend. Donec eros mi, placerat
  in porta eleifend, placerat a urna. Pellentesque venenatis neque non turpis
  convallis vehicula. Aliquam aliquet ultricies tincidunt.}}
  \end{flushleft}
  </code></pre>
  
  <p>But it cannot deal with code listings etc. inside of the text.</p>
  
  <p>Thank you for your advice. Sorry if my English wasn't understandable enough.</p>