Use argparse

Closes #2

README.md

@@ -6,8 +6,7 @@ running `curl <url> | bash`
 ## Work in Progress
 
 `netrun` is still experimental; don't rely on its working properly. In
-particular, HTTP response codes are ignored (see #1) and command line syntax is
-not checked (see #2).
+particular, HTTP response codes are ignored (see #1).
 
 ## Try it
 

netrun.py

@@ -1,6 +1,7 @@
 import requests
 import subprocess
 import sys
+import argparse
 
 
 def launch(command, data):
@@ -26,8 +27,10 @@ def yn(question, options="yn"):
 
     return response
 
-
-url = sys.argv[1]
+parser = argparse.ArgumentParser(description="Securely run a script from the Internet")
+parser.add_argument("url", help="URL of the script")
+args = parser.parse_args()
+url = args.url
 
 content = requests.get(url).content