def lofu_or(m,n):
return m or n

Nice! I works.

I leave the full code for anybody interested:

%\usepackage{pythontex} % in preamble
\begin{pythontexcustomcode}{py}
def taulaveritat(hd):
    print(r"\begin{tabular}{c c|c}")
    print(r"$A$ & $B$ &  %s \\ \hline" % hd)
    for m in range(0, 2):
        for n in range(0, 2):
            print(r"%d & %d & %d \\" % (m, n, lofu(m,n)))
    print(r"\end{tabular}")
\end{pythontexcustomcode}

% Adding the next lines to any question we can build any truth table.
% Just changing the return expression and its name on the pyc command:
\begin{pycode}
def lofu(m,n):
    return m or n
\end{pycode}

\pyc{taulaveritat("$OR$")}

So we can use any Python operator to build any truth table as or, and, not, NAND (not(and)), NOR not(ˆ), XOR (ˆ), XNOR not(ˆ)