How to say "else if" (idea)

case $variable {
    a:   (action1)
    b:   (action2)
    c:   (action3)
    default: (default action)
}

This is the same thing as "if a, then action1, else if b, then action2, else if c, then action3 else default action"

As has been pointed out to me, case only works well with very simple conditional statements.