Determine the full outfile pattern for the given account.

        Return None if not specified.

def outpat(self, acc=None):
        """
        Determine the full outfile pattern for the given account.

        Return None if not specified.
        """
        outdir = self.outdir(acc)
        outpat = self.get('outpat', acc=acc)
        return os.path.join(outdir, outpat) if outdir and outpat else None