A latex snippet using tikz to create beautiful token diagrams

sequence.tex

\documentclass[border=1pt,tikz]{standalone}

\usepackage{listofitems}
\usepackage{tikz}
\usetikzlibrary{arrows}
\usetikzlibrary{backgrounds}

\newcounter{attributecount}
\NewDocumentCommand{\attribute}{mm} {
    \draw[black, fill={#1}, rounded corners=6, thick] (0.1, \value{attributecount}+0.12) rectangle (3.9, \value{attributecount}+0.98) node at (2, \value{attributecount}+0.5) {#2};
    \stepcounter{attributecount};
}
\newcounter{tokencount}
\newcounter{maxattribute}
\newenvironment{token} {
    \begin{scope}[shift={(\value{tokencount}*4.1+0.1, 0.1)}]
    \setcounter{attributecount}{0}
    \stepcounter{tokencount}
} {
    \begin{pgfonlayer}{background}
        \draw[black, fill=gray!10, rounded corners=10, thick] (0, 0) rectangle (4, \value{attributecount}+0.1);
    \end{pgfonlayer}
    \end{scope};
    \noindent
    \ifnum\value{attributecount}>\value{maxattribute}
        \setcounter{maxattribute}{\value{attributecount}}
    \fi
}
\newenvironment{sequence}[2] {
    \begin{scope}[shift={(#1, #2)}]
    \setcounter{tokencount}{0}
    \setcounter{maxattribute}{0}
} {
        \draw[black, rounded corners=12, thick] (0, 0) rectangle (\value{tokencount}*4.1+0.1, \value{maxattribute}+0.3);
    \end{scope}
}



\begin{document}

\definecolor{Pink}{HTML}{E16E97}
\definecolor{Blue}{HTML}{3C9CD1}
\definecolor{Yellow}{HTML}{F3AE48}
\definecolor{Green}{HTML}{A0CF67}
\definecolor{Grey}{HTML}{D1D3D4}


\begin{tikzpicture}[scale=1.0]
    \begin{sequence}{0}{0}
        \begin{token}
            \attribute{Green}{a};
            \attribute{Blue}{b};
            \attribute{Green}{c};
            \attribute{Pink}{d};
            \attribute{Grey}{a};
        \end{token}
        \begin{token}
            \attribute{Yellow}{b};
            \attribute{Green}{c};
            \attribute{Grey}{d};
            \attribute{Green}{3};
        \end{token}
        \begin{token}
            \attribute{Green}{b};
            \attribute{Pink}{c};
            \attribute{Yellow}{d};
            \attribute{Blue}{3};
        \end{token}
        \begin{token}
            \attribute{Yellow}{b};
            \attribute{Green}{c};
            \attribute{Grey}{d};
            \attribute{Green}{3};
        \end{token}
    \end{sequence}
\end{tikzpicture}


\end{document}