def calculate_megno(self):
        """
        Return the current MEGNO value.
        Note that you need to call init_megno() before the start of the simulation.
        """
        if self._calculate_megno==0:
            raise RuntimeError("MEGNO cannot be calculated. Make sure to call init_megno() after adding all particles but before integrating the simulation.")

        clibrebound.reb_tools_calculate_megno.restype = c_double
        return clibrebound.reb_tools_calculate_megno(byref(self))
Return the current MEGNO value.
        Note that you need to call init_megno() before the start of the simulation.