\myheading{Soldering a headphones cable}

This is a real story: I tried to repair my headphone's cable, soldering 3 wires with minijack together.
But which is left? Right? I couldn't even find ground wire.
I asked myself, how many ways there are to solder 3 wires to 3-pin minijack?
I could try them all and pick the combination that sounds best.

With Python's itertools module this is just:

\lstinputlisting[style=custompy]{comb/wires3.py}

\lstinputlisting{comb/wires3.txt}

(Just 6 ways.)

What if there are 4 wires?

\lstinputlisting[style=custompy]{comb/wires4.py}

\lstinputlisting{comb/wires4.txt}

(24 ways.)

This is what is called \textit{permutation} in combinatorics.