% Group terms using parentheses.
\providecommand*{\qty}[1]{ \left( {#1} \right) }
+% Group terms using square brackets.
+\providecommand*{\sqty}[1]{ \left[ {#1} \right] }
+
% Create a set from the given elements
\providecommand*{\set}[1]{ \left\lbrace {#1} \right\rbrace }