The "readline" module offers "write_history_file" from readline/history.h "write_history", but there's no "append_history_file" that would invoke "append_history" from the C header.This causes inconveniences when saving history to a file (like shown there:https://docs.python.org/3.5/library/readline.html?highlight=readline#example). Indeed, say you have 2 interpreters (A) and (B) open.- (A) and (B) load the history, composed of (z) lines- you work on both, writing (a) lines in (A) and (b) lines in (b)- you close (A), the history file now has (z)+(a)- you close (B), the history file now has (z)+(b)Therefore (A) history (the (a) lines) is lost. Offering "append_history_file" would be a nice way to fix this problem: having (z)+(a)+(b) in the end would be easy.This is exactly what the attached patch does. With it are tests, doc and an example. I've not updatedMisc/NEWS yet though (no issue #).

New changesetff00588791be by Benjamin Peterson in branch 'default':add readline.append_history_file (closes#22940)https://hg.python.org/cpython/rev/ff00588791be

New changesetc8bcede1b37a by Ned Deily in branch 'default':Issue 22940: fixes to editline supporthttps://hg.python.org/cpython/rev/c8bcede1b37a