recho "A${*:-w}R"
recho "A${*-w}R"
recho "A${*}R"

set -- ""

recho "A${*:-w}R"
recho "A${*-w}R"
recho "A${*}R"

set -- $'\177'

recho "A${*:+w}R"
recho "A${*+w}R"
recho "A${*}R"

recho A${*:+w}R
recho A${*+w}R
recho A${*}R