<li><strong>Argument <codeclass="python hljs"><spanclass="hljs-string">'flags=re.MULTILINE'</span></code> makes <codeclass="python hljs"><spanclass="hljs-string">'^'</span></code> and <codeclass="python hljs"><spanclass="hljs-string">'$'</span></code> match the start/end of each line.</strong></li>
<li><strong>Argument <codeclass="python hljs"><spanclass="hljs-string">'flags=re.DOTALL'</span></code> makes dot also accept newline.</strong></li>
<li><strong>Use <codeclass="python hljs"><spanclass="hljs-string">r'\1'</span></code> or <codeclass="python hljs"><spanclass="hljs-string">'\\1'</span></code> for backreference.</strong></li>
<li><strong>Use<codeclass="python hljs"><spanclass="hljs-string">'?'</span></code>to make an operator non-greedy.</strong></li>
<li><strong>Add<codeclass="python hljs"><spanclass="hljs-string">'?'</span></code>after an operator to make it non-greedy.</strong></li>
<li><strong>For abbreviated weekday and month use <codeclass="python hljs"><spanclass="hljs-string">'%a'</span></code> and <codeclass="python hljs"><spanclass="hljs-string">'%b'</span></code>.</strong></li>
<li><strong>When parsing, <codeclass="python hljs"><spanclass="hljs-string">'%z'</span></code> also accepts <codeclass="python hljs"><spanclass="hljs-string">'±HH:MM'</span></code>.</strong></li>
<li><strong>For abbreviated weekday and month use <codeclass="python hljs"><spanclass="hljs-string">'%a'</span></code> and <codeclass="python hljs"><spanclass="hljs-string">'%b'</span></code>.</strong></li>