docs: def balances_at(self, utxo_confirmations=6, network=None):
          """Return the confirmed, claimed (reserved for a pending, unsigned
          transaction), and available balances, where the threshold for
          confirmed is the value of `utxo_confirmations`.
  
          Args:
            utxo_confirmations (int): the # of confirmations to use when computing
              balances.
            network (str): Type of cryptocurrency.  Can be one of, 'bitcoin', '
              bitcoin_testnet', 'litecoin', 'dogecoin'.
  
          Returns:
            A dict of form { u'available_balance': 0,
                             u'claimed_balance': 0,
                             u'confirmed_balance': 0,
                             u'utxo_confirmations': 0 }
          """
          if not network in SUPPORTED_NETWORKS:
              raise ValueError('Network not valid!')
          return self.resource.available({'utxo_confirmations': utxo_confirmations,
                                          'network': network}).__dict__['data']