Is there any equivalent to the Perl regexes' \K backslash sequence in Python?
<p>Perl's regular expressions have the <a href="http://perldoc.perl.org/perlrebackslash.html#Misc" rel="nofollow"><code>\K</code></a> backslash sequence:</p>

<blockquote>
  <p><strong>\K</strong><br>
  This appeared in perl 5.10.0. Anything matched left of <code>\K</code> is not
  included in <code>$&amp;</code>, and will not be replaced if the pattern is used in a
  substitution. This lets you write <code>s/PAT1 \K PAT2/REPL/x</code> instead of
  <code>s/(PAT1) PAT2/${1}REPL/x</code> or <code>s/(?&lt;=PAT1) PAT2/REPL/x</code>.</p>
  
  <p>Mnemonic: <em>Keep</em>.</p>
</blockquote>

<p>Is there anything equivalent in Python?</p>

<p>The proposed replacement to the Python <code>re</code> module, <a href="https://pypi.python.org/pypi/regex" rel="nofollow">available from <code>pypi</code> under the name <code>regex</code></a>, has this feature. Its canonical source repository and bug tracker are <a href="https://bitbucket.org/mrabarnett/mrab-regex" rel="nofollow">in bitbucket</a>.</p>

<p>This was added in late 2015, in <a href="https://bitbucket.org/mrabarnett/mrab-regex/issues/151/request-k" rel="nofollow">ticket 151</a>; taking an example of its use from that ticket:</p>

<blockquote>
<pre><code>import regex as mrab
&gt;&gt;&gt; bsk = mrab.compile(r'start=&gt;\K.*')
&gt;&gt;&gt; print(bsk.search('boring stuff start=&gt;interesting stuff'))
&lt;regex.Match object; span=(20, 37), match='interesting stuff'&gt;
</code></pre>
</blockquote>

python regex perl