Latex - Liouville space notation for (super)kets and (super)bras

macro.sty

%%%% Ket & bra with double angles - for Liouville space notation
% use the following command to source it in the main tex file:
% \input{macro.sty}
%

\def\lang{\ensuremath{\langle}}
\def\rang{\ensuremath{\rangle}}

\NewDocumentCommand{\braa}{sO{}m}{%
  \IfBooleanTF{#1}
    {\braaext{#3}}
    {\braax[#2]{#3}}%
}

\NewDocumentCommand{\braaext}{m}{%
  \sbox0{%
    \mathsurround=0pt % just for safety
    $\left\lang\vphantom{#1}\right.\kern-\nulldelimiterspace$%
  }%
  \sbox2{\lang}%
  \ifdim\ht0=\ht2
    \lang\kern-.45\wd2 \lang#1\rvert%
  \else
    \left\lang\kern-.6\wd0\left\lang#1\right\rvert\right.%
  \fi
}

\NewDocumentCommand{\braax}{om}{%
  \sbox0{\mathsurround=0pt$#1\lang$}%
  \sbox2{\lang}%
  \ifdim\ht0=\ht2
    \lang\kern-.45\wd2 \lang#2\rvert%
  \else
    \mathopen{#1\lang\kern-.6\wd0 #1\lang}
    #2
    \mathclose{#1\rvert}
  \fi
}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\NewDocumentCommand{\kett}{sO{}m}{%
  \IfBooleanTF{#1}
    {\kettext{#3}}
    {\kettx[#2]{#3}}%
}

\NewDocumentCommand{\kettext}{m}{%
  \sbox0{%
    \mathsurround=0pt % just for safety
    $\left\lang\vphantom{#1}\right.\kern-\nulldelimiterspace$%
  }%
  \sbox2{\lang}%
  \ifdim\ht0=\ht2
    \lvert#1\rang\kern-.45\wd2 \rang%
  \else
    \left\lvert\left.#1\right\rang\kern-.6\wd0\right\rang%
  \fi
}

\NewDocumentCommand{\kettx}{om}{%
  \sbox0{\mathsurround=0pt$#1\lang$}%
  \sbox2{\lang}%
  \ifdim\ht0=\ht2
    \lvert#2\rang\kern-.45\wd2 \rang%
  \else
    \mathopen{#1\lvert}
    #2
    \mathclose{#1\rang\kern-.6\wd0 #1\rang}
  \fi
}