<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def set_ram(self, ram):
 """ Set the amount of RAM allocated to this VirtualBox VM. :param ram: amount RAM in MB (integer) """


        if ram == 0:
            return

        yield from self._modify_vm('--memory {}'.format(ram))

        log.info("VirtualBox VM '{name}' [{id}] has set amount of RAM to {ram}".format(name=self.name, id=self.id, ram=ram))
        self._ram = ram