bpo-12403: Mention sys.displayhook in code module docs and the compile builtin docs

Doc/library/code.rst

@@ -65,6 +65,32 @@ build applications which provide an interactive interpreter prompt.
    raises :exc:`OverflowError` or :exc:`ValueError` if the command contains an
    invalid literal.
 
+Overriding Console Output
+-------------------------
+
+The output for :class:`InteractiveConsole` and :class:`InteractiveInterpreter`
+is written using one of :data:`sys.stderr`, :func:`sys.displayhook`
+or :func:`sys.excepthook`. Which output mechanism is used depends on the
+reason for producing output:
+
+* The return value from successfully interpreted Python statements are printed
+  by calling :func:`sys.displayhook`. This is a side effect of
+  :func:`compile_command` passing ``'single'`` for *symbol*.
+* If the default :func:`sys.excepthook` has not been replaced, syntax errors
+  and exception tracebacks are printed by calling the
+  :meth:`write <io.TextIOBase.write>` method on :data:`sys.stderr`.
+* If :func:`sys.excepthook` has been replaced with a user defined function
+  :func:`sys.excepthook` is called to handle printing of exception tracebacks
+  and syntax errors.
+
+Additionally, :class:`InteractiveConsole` will print banner information to
+:data:`sys.stderr` if *banner* was passed to the constructor.
+
+To customize the console output a user should replace :func:`sys.displayhook`
+and :func:`sys.excepthook` with custom implementations. Alternatively, users
+can replace the :meth:`InteractiveConsole.write` method on a subclass
+instead of replacing :func:`sys.excepthook` to control the printing of errors.
+
 
 .. _interpreter-objects:
 

Doc/library/functions.rst

@@ -288,8 +288,9 @@ are always available.  They are listed here in alphabetical order.
    The *mode* argument specifies what kind of code must be compiled; it can be
    ``'exec'`` if *source* consists of a sequence of statements, ``'eval'`` if it
    consists of a single expression, or ``'single'`` if it consists of a single
-   interactive statement (in the latter case, expression statements that
-   evaluate to something other than ``None`` will be printed).
+   interactive statement.  In the latter case, expression statements that
+   evaluate to something other than ``None`` will be printed using
+   :func:`sys.displayhook`.
 
    The optional arguments *flags* and *dont_inherit* control which
    :ref:`compiler options <ast-compiler-flags>` should be activated

Misc/NEWS.d/next/Documentation/2021-05-25-20-35-37.bpo-12403.8BFtwS.rst

@@ -0,0 +1 @@
+Update to documentation.