\xx {Rust is}{}{Hello}{ world}{}
\xx {}{Hello world}{Rust}{ is a}{}
\xx {}{Rust is}{a}{ fun}{}
\xx {}{Rust is a}{fun}{ language}{}
\xx {}{world Rust}{is}{ a fun}{}
\xx {}{is a fun}{language}{}{}
\xx {is}{Hello}{world}{ Rust}{}
