lru cache
lru := NewLRU()
## set max capacity
lru.SetMaxCap(10)
## set key value
lru.Set("key1", "value1")
lru.Set("key2", "value2")
## get key value
val := lru.Get("key1").(string)
println(val)
## remove one key
lru.Remove("key1")
## clear lru cache
lru.Clear()