dnl "m4.texinfo": 673: Origin here
define(`foo', `Expansion one.')
dnl =>
foo
dnl =>Expansion one.
pushdef(`foo', `Expansion two.')
dnl =>
foo
dnl =>Expansion two.
popdef(`foo')
dnl =>
foo
dnl =>Expansion one.
popdef(`foo')
dnl =>
foo
dnl =>foo
