feat(sui): Add contract example code (#313)

Author: m30m

pages/price-feeds/use-real-time-data/sui.mdx

@@ -86,7 +86,7 @@ const tx = new TransactionBlock();
 const priceInfoObjectIds = await client.updatePriceFeeds(tx, priceFeedUpdateData, priceIds);
 
 tx.moveCall({
-    target: `YOUR_PACKAGE::YOUR_MODULE::use_pyth_for_defi`,
+    target: `pyth_example::main::use_pyth_price`,
     arguments: [
         ..., // other arguments needed for your contract
         tx.object(pythStateId),
@@ -106,7 +106,43 @@ const result = await wallet.signAndExecuteTransactionBlock(txBlock);
 ```
 
 By calling the `updatePriceFeeds` function, the `SuiPythClient` adds the necessary transactions to the transaction block to update the price feeds.
-Now in your contract you can consume the price by calling `pyth::get_price` or other utility functions on the `PriceInfoObject`.
+Now in your contract you can consume the price by calling `pyth::get_price` or other utility functions on the `PriceInfoObject`:
+
+```rust copy
+module pyth_example::main {
+    use sui::clock::Clock;
+    use pyth::price_info;
+    use pyth::price_identifier;
+    use pyth::price;
+    use pyth::state::{State as PythState};
+    use pyth::pyth;
+    use pyth::price_info::PriceInfoObject;
+
+    const E_INVALID_ID: u64 = 1;
+
+    public fun use_pyth_price(
+        // other arguments
+        clock: &Clock,
+        pyth_state: &PythState,
+        price_info_object: &PriceInfoObject,
+    ){
+        let max_age = 60;
+        // make sure the price is not older than max_age seconds
+        let price_struct = pyth::get_price(pyth_state,price_info_object, clock);
+
+        // check the price feed id
+        let price_info = price_info::get_price_info_from_price_info_object(price_info_object);
+        let price_id = price_identifier::get_bytes(&price_info::get_price_identifier(&price_info));
+        // ETH/USD price feed id
+        assert!(price_id!=x"ff61491a931112ddf1bd8147cd1b641375f79f5825126d665480874634fd0ace", E_INVALID_ID);
+
+        // extract the price, decimal, and timestamp from the price struct and use them
+        let decimal_i64 = price::get_expo(&price_struct);
+        let price_i64 = price::get_price(&price_struct);
+        let timestamp_sec = price::get_timestamp(&price_struct);
+    }
+}
+```
 
 ### Pyth Dependency