diff --git a/echo.py b/echo.py
index 1c58b3a..14990ab 100644
--- a/echo.py
+++ b/echo.py
@@ -1,17 +1,40 @@
 import sys
 
 import requests
+import asyncio
 
 from rich.console import Console
 from rich.markdown import Markdown
 
 console = Console()
 
-def main():
-    args = sys.argv[-1]
-    resp = requests.get(args)
-    console.print(Markdown(resp.text))
+
+async def fetch_content_async(url):
+    loop = asyncio.get_event_loop()
+    response = await loop.run_in_executor(None, requests.get, url)
+    return response
+
+
+def fetch_content_sync(url):
+    response = requests.get(url)
+    return response
+
+
+async def main():
+    if len(sys.argv) < 2:
+        console.print("Error: URL is missing!")
+        return
+
+    url = sys.argv[-1]
+
+    # sync request
+    response_sync = fetch_content_sync(url)
+    console.print(Markdown(response_sync.text))
+
+    # async
+    response_async = await fetch_content_async(url)
+    console.print(Markdown(response_async.text))
 
 
 if __name__ == "__main__":
-    main()
+    asyncio.run(main())
\ No newline at end of file
diff --git a/test_echo.py b/test_echo.py
new file mode 100644
index 0000000..4ac4a7f
--- /dev/null
+++ b/test_echo.py
@@ -0,0 +1,36 @@
+import unittest
+from unittest.mock import patch, MagicMock
+import asyncio
+from echo import fetch_content_sync, fetch_content_async
+
+
+class TestMain(unittest.TestCase):
+
+    @patch('requests.get')
+    def test_fetch_content_sync(self, mock_get):
+        mock_response = MagicMock()
+        mock_response.text = "# Mocked Markdown Response"
+        mock_get.return_value = mock_response
+
+        url = "https://example.com"
+        response = fetch_content_sync(url)
+
+        mock_get.assert_called_with(url)
+        self.assertEqual(response.text, "# Mocked Markdown Response")
+
+    @patch('requests.get')
+    def test_fetch_content_async(self, mock_get):
+        mock_response = MagicMock()
+        mock_response.text = "# Mocked Async Markdown Response"
+        mock_get.return_value = mock_response
+
+        url = "https://example.com"
+
+        response = asyncio.run(fetch_content_async(url))
+
+        mock_get.assert_called_with(url)
+        self.assertEqual(response.text, "# Mocked Async Markdown Response")
+
+
+if __name__ == '__main__':
+    unittest.main()
\ No newline at end of file