diff --git a/01.workspace/heave/src/str/entity.rs b/01.workspace/heave/src/str/entity.rs
index 0dbe0d5..e1a57f0 100644
--- a/01.workspace/heave/src/str/entity.rs
+++ b/01.workspace/heave/src/str/entity.rs
@@ -12,9 +12,17 @@ impl O {
         Self {
             id: short_uuid::short!().to_string(),
             class: String::from(class),
-            attributes: std::collections::HashMap::new(),
+            ..Entity::default()
         }
     }
+    pub fn with_id(mut self, id: &str) -> Self {
+        self.id = id.to_string();
+        self
+    }
+    pub fn with_class(mut self, class: &str) -> Self {
+        self.class = class.to_string();
+        self
+    }
     pub fn with_attribute(mut self, id: &str, value: impl ToValue) -> Self {
         let attribute = Attribute::new(id, value);
         self.attributes.insert(attribute.id.clone(), attribute);
diff --git a/01.workspace/heave/src/tst/intended_use.rs b/01.workspace/heave/src/tst/intended_use.rs
index 688db0b..43082a4 100644
--- a/01.workspace/heave/src/tst/intended_use.rs
+++ b/01.workspace/heave/src/tst/intended_use.rs
@@ -3,12 +3,15 @@ mod tests {
     use crate::*;
     #[derive(Debug, Clone, PartialEq)]
     struct Product {
+        pub id: String,
         pub name: String,
         pub price: u64,
     }
     impl ToEAV for Product {
         fn to_eav(self) -> Entity {
-            Entity::new("product")
+            Entity::default()
+                .with_class("product")
+                .with_id(&self.id)
                 .with_attribute("name", self.name)
                 .with_attribute("price", self.price)
         }
@@ -16,6 +19,7 @@ mod tests {
     impl FromEAV for Product {
         fn from_eav(entity: Entity) -> Product {
             Product {
+                id: entity.id.clone(),
                 name: entity.unwrap("name"),
                 price: entity.unwrap("price"),
             }
@@ -108,6 +112,7 @@ mod tests {
     #[test]
     fn check_006() {
         let product = Product {
+            id: "abcdef".to_string(),
             name: "laptop".to_string(),
             price: 200000u64,
         };