\newenvironment{sproof}{%
    \begin{tabbing}
    \phantom{$\equiv$} \= \qquad\qquad\qquad\qquad\qquad \= \kill
}{
    \end{tabbing}
}
\newcommand{\stmt}[1]{\> \ensuremath{#1} \\}
\newcommand{\lstmt}[1]{\> \ensuremath{#1} }
\newcommand{\reason}[2]{\ensuremath{#1} \>\> \{ \quad #2 \quad \} \\}

\newcommand{\subpart}[1]{\llcorner #1 \lrcorner}
\newcommand{\suppart}[1]{\ulcorner #1 \urcorner}

