initial code (#6)

* initial code commit

cache/delete.go

@@ -0,0 +1,15 @@
+package cache
+
+import (
+	"fmt"
+	"github.com/xujiajun/nutsdb"
+)
+
+func (c *Client) Delete(bucket string, key string) error {
+	if err := c.db.Update(func(tx *nutsdb.Tx) error {
+		return tx.Delete(bucket, []byte(key))
+	}); err != nil {
+		return fmt.Errorf("%v: %v; delete: %w", bucket, key, err)
+	}
+	return nil
+}