Add simple CLI

gitfiler/__main__.py

@@ -0,0 +1,20 @@
+import argparse
+import sys
+from . import gitfiler
+from .exceptions import InvalidURL, UnsupportedURL
+
+parser = argparse.ArgumentParser(
+    prog="gitfiler",
+    description="GitHub/GitLab single file downloader.",
+    allow_abbrev=False,
+)
+parser.add_argument(dest="URL")
+args = parser.parse_args()
+
+try:
+    file_ = gitfiler(args.URL)
+    file_content = file_.text
+    print(file_content)
+except (InvalidURL, UnsupportedURL) as e:
+    print(f"{parser.prog}: error: {e}")
+    sys.exit(1)