heckout.html">git-checkout(1)</a> or
<a href="git-switch.html">git-switch(1)</a> is run after having updated the
worktree.  The hook is given three parameters: the ref of the previous HEAD,
the ref of the new HEAD (which may or may not have changed), and a flag
indicating whether the checkout was a branch checkout (changing branches,
flag=1) or a file checkout (retrieving a file from the index, flag=0).
This hook cannot affect the outcome of <code>git switch</code> or <code>git checkout</code>,
other than t