Finished Lesson 3

.gitignore

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+.env

check-balance.ts

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+import "dotenv/config";
+import {
+    Connection,
+    LAMPORTS_PER_SOL,
+    PublicKey,
+    clusterApiUrl,
+} from "@solana/web3.js";
+
+const key = process.argv[2];
+
+const connection = new Connection(clusterApiUrl("devnet"));
+console.log('connected to devnet')
+
+const publicKey = new PublicKey(key);
+const balanceInLamPorts = await connection.getBalance(publicKey);
+
+const balanceInSol = balanceInLamPorts / LAMPORTS_PER_SOL;
+
+console.log('Finished! There is', balanceInSol, 'SOL on wallet', key);