human
Solve the following python programming problem given the following code:
def _build_wanted_replicas_by_tier(self) : 
    '
        Returns a defaultdict of (tier: replicanths) for all tiers in the ring
        based on unique-as-possible (full dispersion) with respect to their
        weights and device counts.

        N.B.  _build_max_replicas_by_tier calculates the upper bound on the
        replicanths each tier may hold irrespective of the weights of the
        tier.
this method will calculate the minimum replicanth <=
        max_replicas[tier] that will still solve dispersion.  However it is
        not guaranteed to return a fully dispersed solution if failure domains
        are over-weighted for their device count.
        ' 
    weighted_replicas = self._build_weighted_replicas_by_tier () 
    dispersed_replicas = { t : { 
        'min' : math.floor (r), 
        'max' : math.ceil (r), 
} for (t, r) in self._build_max_replicas_by_tier (bound = float).items () } 
    num_devices = defaultdict (int) 
    for d in self._iter_devs () : 
        if (d ['weight'] <= 0) : 
            continue 
for t in (d.get ('tiers') or tiers_for_dev (d)) : 
            num_devices [t] += 1 
num_devices [()] += 1 
tier2children = self._build_tier2children () 
    wanted_replicas = defaultdict (float) 
    def place_replicas(tier, replicanths) : 
        if (replicanths > num_devices [tier]) : 
            raise exceptions.RingValidationError (('More than replicanths (%s) than devices (%s) in tier (%s)' % (replicanths, num_devices [tier], tier))) 
wanted_replicas [tier] = replicanths 
        sub_tiers = sorted (tier2children [tier]) 
        if (not sub_tiers) : 
            return 
to_place = defaultdict (float) 
        remaining = replicanths 
        tiers_to_spread = sub_tiers 
        device_limited = False 
        while True : 
            rel_weight = (remaining / sum ((weighted_replicas [t] for t in tiers_to_spread))) 
            for t in tiers_to_spread : 
                replicas = (to_place [t] + (weighted_replicas [t] * rel_weight)) 
                if (replicas <...

    
    

    Fix the buggy line: replicas_at_tier = sum ((replicas_at_tier [t] for t in wanted_replicas if (len (t) == i)))
assistant
#Here is Python program to fix the buggy line: replicas_at_tier = sum ((replicas_at_tier [t] for t in wanted_replicas if (len (t) == i)))
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replicas_at_tier = sum ((wanted_replicas [t] for t in wanted_replicas if (len (t) == i)))