manage exiting without external dependency

comment.py

@@ -19,7 +19,6 @@ import antlr4
 import configparser
 import logging
 import readline
-import signal
 import sys
 
 from CommentMacroLexer import CommentMacroLexer
@@ -58,20 +57,18 @@ def comment(text):
     walker.walk(oscMacro, tree)
 
 
-def orderly_exit():
-    logger.info('Goodbye.')
-    sys.exit(0)
-
-
 if __name__ == '__main__':
-    signal.signal(signal.SIGINT, orderly_exit)
     if len(sys.argv) > 1:
         logger.debug("found macro at argv[1]")
         comment(sys.argv[1])
     else:
         while True:
-            text = input("comment# ")
+            try:
+                text = input("comment# ")
+            except KeyboardInterrupt:
+                print()
+                sys.exit(0)
             if text == 'exit':
-                orderly_exit()
+                sys.exit(0)
             else:
                 comment(text)