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	diff --git a/memo/memo.go b/memo/memo.go
	new file mode 100644
	index 0000000..8592b17
	--- /dev/null
	+++ b/memo/memo.go
	@@ -0,0 +1,56 @@
	+package memo
	+
	+import (
	+ "sync"
	+)
	+
	+type (
	+ Memo struct {
	+ f Func
	+ mu sync.Mutex //guards cache
	+ cache *entry
	+ }
	+
	+ Func func() (interface{}, error)
	+)
	+
	+type (
	+ entry struct {
	+ res result
	+ ready chan struct{} // close when res is read
	+ }
	+
	+ result struct {
	+ value interface{}
	+ err error
	+ }
	+)
	+
	+func New(f Func) *Memo {
	+ return &Memo{
	+ f: f,
	+ }
	+}
	+
	+func (memo *Memo) Invalidate() {
	+ memo.mu.Lock()
	+ memo.cache = nil
	+ memo.mu.Unlock()
	+}
	+
	+func (memo *Memo) Get() (value interface{}, err error) {
	+ memo.mu.Lock()
	+ if memo.cache == nil {
	+ memo.cache = &entry{ready: make(chan struct{})}
	+ memo.mu.Unlock()
	+
	+ memo.cache.res.value, memo.cache.res.err = memo.f()
	+
	+ close(memo.cache.ready)
	+ } else {
	+ memo.mu.Unlock()
	+
	+ <-memo.cache.ready
	+ }
	+ return memo.cache.res.value, memo.cache.res.err
	+}