Obtain the r-shares
            :param number sp: Steem Power
            :param int voting_power: voting power (100% = 10000)
            :param int vote_pct: voting participation (100% = 10000)

def sp_to_rshares(self, sp, voting_power=10000, vote_pct=10000):
        """ Obtain the r-shares
            :param number sp: Steem Power
            :param int voting_power: voting power (100% = 10000)
            :param int vote_pct: voting participation (100% = 10000)
        """
        vesting_shares = int(self.sp_to_vests(sp) * 1e6)
        used_power = int((voting_power * vote_pct) / 10000);
        max_vote_denom = self.vote_power_reserve_rate * (5 * 60 * 60 * 24) / (60 * 60 * 24);
        used_power = int((used_power + max_vote_denom - 1) / max_vote_denom)
        rshares = ((vesting_shares * used_power) / 10000)
        return rshares