func (p BalanceStrategyPlan) Add(memberID, topic string, partitions ...int32) {
	if len(partitions) == 0 {
		return
	}
	if _, ok := p[memberID]; !ok {
		p[memberID] = make(map[string][]int32, 1)
	}
	p[memberID][topic] = append(p[memberID][topic], partitions...)
}
Add assigns a topic with a number partitions to a member.
package sarama
import (
	"container/heap"
	"errors"
	"fmt"
	"math"
	"sort"
	"strings"
)
const (
	RangeBalanceStrategyName = "range"
	RoundRobinBalanceStrategyName = "roundrobin"
	StickyBalanceStrategyName = "sticky"
	defaultGeneration = -1
)
type BalanceStrategyPlan map[string]map[string][]int32