docs: def getDepth(pair, connection=None, info=None):
      """Retrieve the depth for the given pair.  Returns a tuple (asks, bids);
      each of these is a list of (price, volume) tuples."""
  
      if info is not None:
          info.validate_pair(pair)
  
      if connection is None:
          connection = common.BTCEConnection()
  
      response = connection.makeJSONRequest("/api/3/depth/%s" % pair)
      if type(response) is not dict:
          raise TypeError("The response is not a dict.")
  
      depth = response.get(pair)
      if type(depth) is not dict:
          raise TypeError("The pair depth is not a dict.")
  
      asks = depth.get(u'asks')
      if type(asks) is not list:
          raise TypeError("The response does not contain an asks list.")
  
      bids = depth.get(u'bids')
      if type(bids) is not list:
          raise TypeError("The response does not contain a bids list.")
  
      return asks, bids