Parse each returned registry value.

def ParseMultiple(self, stats, knowledge_base):
    """Parse each returned registry value."""
    user_dict = {}

    for stat in stats:
      sid_str = stat.pathspec.path.split("/", 3)[2]
      if SID_RE.match(sid_str):
        if sid_str not in user_dict:
          user_dict[sid_str] = rdf_client.User(sid=sid_str)

        if stat.registry_data.GetValue():
          # Look up in the mapping if we can use this entry to populate a user
          # attribute, and if so, set it.
          reg_key_name = stat.pathspec.Dirname().Basename()
          if reg_key_name in self.key_var_mapping:
            map_dict = self.key_var_mapping[reg_key_name]
            reg_key = stat.pathspec.Basename()
            kb_attr = map_dict.get(reg_key)
            if kb_attr:
              value = artifact_utils.ExpandWindowsEnvironmentVariables(
                  stat.registry_data.GetValue(), knowledge_base)
              value = artifact_utils.ExpandWindowsUserEnvironmentVariables(
                  value, knowledge_base, sid=sid_str)
              user_dict[sid_str].Set(kb_attr, value)

    # Now yield each user we found.
    return itervalues(user_dict)