chore: Add fetch block and fetch block range examples

hermes/crates/cardano-chain-follower/examples/fetch_block.rs

@@ -0,0 +1,37 @@
+//! This example shows how to use the chain follower to download arbitrary blocks
+//! from the chain.
+
+use std::error::Error;
+
+use cardano_chain_follower::{ConfigBuilder, Follower, Network, Point};
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn Error>> {
+    let config = ConfigBuilder::default().build();
+
+    let mut follower = Follower::connect(
+        "relays-new.cardano-mainnet.iohk.io:3001",
+        Network::Mainnet,
+        config,
+    )
+    .await?;
+
+    let data = follower
+        .fetch_block(Point::Specific(
+            110908236,
+            hex::decode("ad3798a1db2b6097c71f35609399e4b2ff834f0f45939803d563bf9d660df2f2")?,
+        ))
+        .await?;
+
+    let block = data.decode()?;
+
+    let total_fee = block
+        .txs()
+        .iter()
+        .map(|tx| tx.fee().unwrap_or_default())
+        .sum::<u64>();
+
+    println!("Total fee: {total_fee}");
+
+    Ok(())
+}

hermes/crates/cardano-chain-follower/examples/fetch_block_range.rs

@@ -0,0 +1,41 @@
+//! This example shows how to use the chain follower to download arbitrary blocks
+//! from the chain.
+
+use std::error::Error;
+
+use cardano_chain_follower::{ConfigBuilder, Follower, Network, Point};
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn Error>> {
+    let config = ConfigBuilder::default().build();
+
+    let mut follower = Follower::connect(
+        "relays-new.cardano-mainnet.iohk.io:3001",
+        Network::Mainnet,
+        config,
+    )
+    .await?;
+
+    let datas = follower
+        .fetch_block_range(
+            Point::Specific(
+                110908236,
+                hex::decode("ad3798a1db2b6097c71f35609399e4b2ff834f0f45939803d563bf9d660df2f2")?,
+            ),
+            Point::Specific(
+                110908582,
+                hex::decode("16e97a73e866280582ee1201a5e1815993978eede956af1869b0733bedc131f2")?,
+            ),
+        )
+        .await?;
+
+    let mut total_txs = 0;
+    for data in datas {
+        let block = data.decode()?;
+        total_txs = block.tx_count();
+    }
+
+    println!("Total transactions: {total_txs}");
+
+    Ok(())
+}