<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def __sum_stats(self, key, indice=None, mmm=None):
 """Return the sum of the stats value for the given key. * indice: If indice is set, get the p[key][indice] * mmm: display min, max, mean or current (if mmm=None) """

        # Compute stats summary
        ret = 0
        for p in self.stats:
            if key not in p:
                # Correct issue #1188
                continue
            if p[key] is None:
                # Correct https://github.com/nicolargo/glances/issues/1105#issuecomment-363553788
                continue
            if indice is None:
                ret += p[key]
            else:
                ret += p[key][indice]

        # Manage Min/Max/Mean
        mmm_key = self.__mmm_key(key, indice)
        if mmm == 'min':
            try:
                if self.mmm_min[mmm_key] > ret:
                    self.mmm_min[mmm_key] = ret
            except AttributeError:
                self.mmm_min = {}
                return 0
            except KeyError:
                self.mmm_min[mmm_key] = ret
            ret = self.mmm_min[mmm_key]
        elif mmm == 'max':
            try:
                if self.mmm_max[mmm_key] < ret:
                    self.mmm_max[mmm_key] = ret
            except AttributeError:
                self.mmm_max = {}
                return 0
            except KeyError:
                self.mmm_max[mmm_key] = ret
            ret = self.mmm_max[mmm_key]

        return ret