upcast int to size_t to silence two autological-constant-out-of-range-compare warnings with clang.
ncurses' winch and mvwinch return an unsigned long
ncurses' winch and mvwinch return an unsigned long
Silence expression result unused warnings with clang.
The PyObject_INIT() macros returns obj:

../cpython/Objects/methodobject.c:32:23: warning: expression result unused [-Wunused-value]
        PyObject_INIT(op, &PyCFunction_Type);
                      ^~
../cpython/Include/objimpl.h:139:69: note: expanded from macro 'PyObject_INIT'
    ( Py_TYPE(op) = (typeobj), _Py_NewReference((PyObject *)(op)), (op) )
                                                                    ^
1 warning generated.
make char* const
readline() takes a const char* and the other readline_until_enter_or_signal() implementation
already has const char*.
Silence more PyObject_INIT() unused value warnings.
silence unused-value warnings in libffi's dlmalloc.c
asyncio doc: add some notes on the ping example