Selective export (#770)

vendor/github.com/modern-go/concurrent/go_below_19.go

@@ -4,17 +4,20 @@ package concurrent
 
 import "sync"
 
+// Map implements a thread safe map for go version below 1.9 using mutex
 type Map struct {
 	lock sync.RWMutex
 	data map[interface{}]interface{}
 }
 
+// NewMap creates a thread safe map
 func NewMap() *Map {
 	return &Map{
 		data: make(map[interface{}]interface{}, 32),
 	}
 }
 
+// Load is same as sync.Map Load
 func (m *Map) Load(key interface{}) (elem interface{}, found bool) {
 	m.lock.RLock()
 	elem, found = m.data[key]
@@ -22,9 +25,9 @@ func (m *Map) Load(key interface{}) (elem interface{}, found bool) {
 	return
 }
 
+// Load is same as sync.Map Store
 func (m *Map) Store(key interface{}, elem interface{}) {
 	m.lock.Lock()
 	m.data[key] = elem
 	m.lock.Unlock()
 }
-