@@ -0,0 +1,27 @@
+#!/usr/bin/env python
+# Purpose: Say hello
+
+import sys
+
+def usage(message:str = 'Program run without any arguments') -> None:
+  print(message + '\nusage: hello.py NAME')
+
+def greet(name:str = 'World') -> str:
+  return f'Hello, {name}!'
+
+def test_greet() -> None:
+  assert greet() == 'Hello, World!'
+  assert greet('Terra Firma') == 'Hello, Terra Firma!'
+
+def main() -> None:
+  if len(sys.argv) == 1:
+    usage()
+    sys.exit(1)
+  elif len(sys.argv) > 2:
+    usage('Program called with too many arguments')
+    sys.exit(1)
+  
+  print(greet(sys.argv[1]))
+  
+if __name__ == '__main__':
+  main()