docs: def drop_index(self, raw):
          """ Executes a drop index command.
  
              { "op" : "c",
                "ns" : "testdb.$cmd",
                "o" : { "dropIndexes" : "testcoll",
              		  "index" : "nuie_1" } }
          """
          dbname = raw['ns'].split('.', 1)[0]
          collname = raw['o']['dropIndexes']
          self.dest[dbname][collname].drop_index(raw['o']['index'])