First model change (#23)

Reviewed-on: #23
Co-authored-by: phoenix <kundeng94@gmail.com>
Co-committed-by: phoenix <kundeng94@gmail.com>

src/lib.rs

@@ -7,3 +7,25 @@ pub mod song;
 pub mod token;
 pub mod types;
 pub mod user;
+
+pub mod init {
+    pub fn is_id_valid(num: &i32) -> bool {
+        *num > 0
+    }
+
+    pub fn is_uuid_nil(uuid: &uuid::Uuid) -> bool {
+        uuid.is_nil()
+    }
+
+    pub fn is_zero(num: &i32) -> bool {
+        *num == 0
+    }
+
+    pub fn is_dur_not_set(num: &i32) -> bool {
+        *num == 0
+    }
+
+    pub fn is_set(num: &i32) -> bool {
+        *num >= 0
+    }
+}