Mark required arguments in scripts as required

hocr2tei

@@ -12,7 +12,8 @@ import re
 parser = ArgumentParser(description='Convert hOCR to TEI XML.')
 parser.add_argument(
     '-i', '--input-file',
-    help='Input file'
+    help='Input file',
+    required=True
 )
 parser.add_argument(
     '-o', '--output-file',