add comment about \001 and \002

Author: tanloong

Lib/sqlite3/__main__.py

@@ -133,11 +133,15 @@ def main(*args):
     s = theme.syntax
 
     if s.prompt:
+        # Use RL_PROMPT_START_IGNORE (\001) and RL_PROMPT_END_IGNORE (\002) to
+        # bracket non-printing characters. This tells readline to ignore them
+        # when calculating screen space for redisplay during history scrolling.
+        # See https://stackoverflow.com/a/9468954 for more details.
         sys.ps1 = f"\001{s.prompt}\002sqlite> \001{s.reset}\002"
         sys.ps2 = f"\001{s.prompt}\002    ... \001{s.reset}\002"
     else:
-        sys.ps1 = f"sqlite> "
-        sys.ps2 = f"    ... "
+        sys.ps1 = "sqlite> "
+        sys.ps2 = "    ... "
 
     con = sqlite3.connect(args.filename, isolation_level=None)
     try: