dnl ../doc/m4.texinfo:1229: Origin of test
define(`foo', `Expansion one.')
dnl @result{}
foo
dnl @result{}Expansion one.
pushdef(`foo', `Expansion two.')
dnl @result{}
foo
dnl @result{}Expansion two.
define(`foo', `Second expansion two.')
dnl @result{}
foo
dnl @result{}Second expansion two.
undefine(`foo')
dnl @result{}
foo
dnl @result{}foo