def expire(ttl)
      ttl = (ttl.to_f * 1000).floor
      return coerce_bool(self.connection.pexpire(@key, ttl))
    end
def expire(ttl)
      ttl = (ttl.to_f * 1000).floor
      return coerce_bool(self.connection.pexpire(@key, ttl))
    end
Sets the key to expire after ttl seconds
 @param [#to_f] ttl the time to live in seconds (where 0.001 = 1ms)
 @return [Boolean] true if expired, false otherwise