docs: def eval_from_json(json):
          """ Evaluates OBV from JSON (typically Poloniex API response)
  
          Args:
              json: List of dates where each entry is a dict of raw market data.
  
          Returns:
              Float of OBV
          """
          closes = poloniex.get_attribute(json, 'close')
          volumes = poloniex.get_attribute(json, 'volume')
          obv = 0
          for date in range(1, len(json)):
              curr = {'close': closes[date], 'volume': volumes[date]}
              prev = {'close': closes[date - 1], 'obv': obv}
              obv = OBV.eval_algorithm(curr, prev)
          return obv