var</span><span class='op'>(</span><span class='va'>data</span>, <span class='va'>expr</span>, <span class='va'>...</span><span class='op'>)</span>

<span class='fu'>hide_var</span><span class='op'>(</span><span class='va'>data</span>, <span class='va'>...</span><span class='op'>)</span>

<span class='fu'>show_var</span><span class='op'>(</span><span class='va'>data</span>, <span class='va'>...</span><span class='op'>)</span>

<span class='fu'>colour_var</span><span class='op'>(</span><span class='va'>data<