How to use the benchexec.util.find_executable function in BenchExec

def preprocessSourcefile(self, sourcefile):
        gotoCcExecutable      = util.find_executable('goto-cc')
        # compile with goto-cc to same file, bith '.cc' appended
        self.preprocessedFile = sourcefile + ".cc"

        subprocess.Popen([gotoCcExecutable,
                            sourcefile,
                            '-o',
                            self.preprocessedFile],
                          stdout=subprocess.PIPE).wait()

        return self.preprocessedFile

def executable(self):
        return util.find_executable("predatorHP.py")

def executable(self):
        return util.find_executable("pagai")

def executable(self):
        return util.find_executable("tbf", "bin/tbf")

def executable(self):
        return util.find_executable('acsar')

def executable(self):
        return util.find_executable("lazy-cseq.py")

def executable(self):
        return util.find_executable("wolverine")

def executable(self):
        executable = util.find_executable('cpa.sh', 'scripts/cpa.sh')
        executableDir = os.path.join(os.path.dirname(executable), os.path.pardir)
        if os.path.isdir(os.path.join(executableDir, 'src')):
            self._buildCPAchecker(executableDir)
        if not os.path.isfile(os.path.join(executableDir, "cpachecker.jar")):
            logging.warning("Required JAR file for CPAchecker not found in {0}.".format(executableDir))
        return executable

def executable(self):
        return util.find_executable("cbmc")

def executable(self):
        return util.find_executable("tabol.sh")