diff --git a/01.workspace/heave/src/str/catalog.rs b/01.workspace/heave/src/str/catalog.rs
index 1a134e9..91fc33b 100644
--- a/01.workspace/heave/src/str/catalog.rs
+++ b/01.workspace/heave/src/str/catalog.rs
@@ -13,11 +13,11 @@ impl O {
             ..O::default()
         }
     }
-    pub fn insert(&mut self, object: impl ToEAV) {
+    pub fn insert(&mut self, object: impl EAV) {
         let entity = object.to_eav();
         self.items.insert(entity.id.clone(), entity);
     }
-    pub fn insert_many(&mut self, objects: Vec<impl ToEAV>) {
+    pub fn insert_many(&mut self, objects: Vec<impl EAV>) {
         for object in objects {
             let entity = object.to_eav();
             self.items.insert(entity.id.clone(), entity);
diff --git a/01.workspace/heave/src/tst/mod.rs b/01.workspace/heave/src/tst/mod.rs
index 84b3ec7..3a63fa1 100644
--- a/01.workspace/heave/src/tst/mod.rs
+++ b/01.workspace/heave/src/tst/mod.rs
@@ -1,3 +1,4 @@
 pub mod entity_new;
 pub mod entity_with_attribute;
 pub mod intended_use;
+pub mod rusty_budger_use;
diff --git a/01.workspace/heave/src/tst/rusty_budger_use.rs b/01.workspace/heave/src/tst/rusty_budger_use.rs
new file mode 100644
index 0000000..bce6582
--- /dev/null
+++ b/01.workspace/heave/src/tst/rusty_budger_use.rs
@@ -0,0 +1,119 @@
+#[cfg(test)]
+mod tests {
+    use crate::*;
+    use category::*;
+    use operation::*;
+    use relation::*;
+    pub mod relation {
+        use super::*;
+        pub struct OperationToCategory {
+            pub id: String,
+            pub operation_id: String,
+            pub category_id: String,
+        }
+        impl EAV for OperationToCategory {}
+        impl ToEAV for OperationToCategory {
+            fn to_eav(self) -> Entity {
+                Entity::default()
+                    .with_class("operation_has_category")
+                    .with_id(&self.id)
+                    .with_attribute("operation_id", self.operation_id)
+                    .with_attribute("category_id", self.category_id)
+            }
+        }
+        impl FromEAV for OperationToCategory {
+            fn from_eav(entity: Entity) -> Self {
+                OperationToCategory {
+                    id: entity.id.clone(),
+                    operation_id: entity.unwrap("operation_id"),
+                    category_id: entity.unwrap("category_id"),
+                }
+            }
+        }
+    }
+    pub mod category {
+        use super::*;
+        pub struct Category {
+            pub id: String,
+            pub label: String,
+        }
+        impl EAV for Category {}
+        impl ToEAV for Category {
+            fn to_eav(self) -> Entity {
+                Entity::default()
+                    .with_class("category")
+                    .with_id(&self.id)
+                    .with_attribute("label", self.label)
+            }
+        }
+        impl FromEAV for Category {
+            fn from_eav(entity: Entity) -> Self {
+                Category {
+                    id: entity.id.clone(),
+                    label: entity.unwrap("label"),
+                }
+            }
+        }
+    }
+    pub mod operation {
+        use super::*;
+        pub struct Operation {
+            pub id: String,
+            pub date: u64,
+            pub amount: i64,
+            pub description: String,
+        }
+        impl EAV for Operation {}
+        impl ToEAV for Operation {
+            fn to_eav(self) -> Entity {
+                Entity::default()
+                    .with_class("operation")
+                    .with_id(&self.id)
+                    .with_attribute("date", self.date)
+                    .with_attribute("amount", self.amount)
+                    .with_attribute("description", self.description)
+            }
+        }
+        impl FromEAV for Operation {
+            fn from_eav(entity: Entity) -> Self {
+                Operation {
+                    id: entity.id.clone(),
+                    date: entity.unwrap("date"),
+                    amount: entity.unwrap("amount"),
+                    description: entity.unwrap("description"),
+                }
+            }
+        }
+    }
+    #[test]
+    pub fn check_001() {
+        let mut catalog = Catalog::new("");
+        let operation_01 = Operation {
+            id: short_uuid::short!().to_string(),
+            date: 20250929,
+            amount: -10000,
+            description: "operation 1".to_string(),
+        };
+        let operation_02 = Operation {
+            id: short_uuid::short!().to_string(),
+            date: 20250930,
+            amount: -20000,
+            description: "operation 2".to_string(),
+        };
+        let category_01 = Category {
+            id: short_uuid::short!().to_string(),
+            label: "Need".to_string(),
+        };
+        let relation_01 = OperationToCategory {
+            id: short_uuid::short!().to_string(),
+            operation_id: operation_01.id.clone(),
+            category_id: category_01.id.clone(),
+        };
+        let operations = vec![operation_01, operation_02];
+        let categories = vec![category_01];
+        let relations = vec![relation_01];
+        catalog.insert_many(operations);
+        catalog.insert_many(categories);
+        catalog.insert_many(relations);
+    }
+}