================================================================================
tikzpicture
================================================================================
\begin{tikzpicture}
bar
\end{tikzpicture}
--------------------------------------------------------------------------------
(document
  (tikzpicture_env
    (begin
      (cs)
      (group (l) (name) (r)))
    (text)
    (end
      (cs)
      (group (l) (name) (r)))))

================================================================================
tikzpicture environment with optional parameter
================================================================================
\begin{tikzpicture}[foo]
bar
\end{tikzpicture}
--------------------------------------------------------------------------------
(document
  (tikzpicture_env
    (begin
      (cs)
      (group (l) (name) (r))
      (brack_group (lbrack) (text) (rbrack)))
    (text)
    (end
      (cs)
      (group (l) (name) (r)))))