code: def get_exchange_rate(self, base, target, raise_errors=True):
          
          assert base and target
  
          base, target = base.lower(), target.lower()
  
          r = self.session.get(API_SIMPLE_TICKER.format(base, target))
          if r.status_code != requests.codes.ok:
              if not raise_errors:
                  return None
              raise CryptonatorException(
                  ("An error occurred while getting requested exchange rate "
                   "({} from Cryptonator).").format(r.status_code)
              )
  
          j = r.json()
          if not j['success'] or j['error']:
              if not raise_errors:
                  return None
              raise CryptonatorException(
                  ("An error occurred while getting requested exchange rate ({}, {})"
                   "('{}').").format(base, target, j['error'])
              )
  
          return float(j['ticker']['price'])
docs: Return the ::base:: to ::target:: exchange rate.