func NewMap() (m *Map) {
	m = &Map{}
	m.data = make(map[interface{}]interface{})
	return m
}
NewMap creates a new map with the specified shards count.
If the shards argument is < 2, the DefaultShardCount will be used.
package xz
import "sync"
type Map struct {
	mtx  sync.RWMutex
	data map[interface{}]interface{}
}