Why am I getting this error "string$-$trim: undefined;

cannot reference an identifier before its definition"?

$($define $($valid$-$whoozit? s$)$

$($and $(=($string$-$ref s $0)$ #$\backslash$x$)$

$(>($string$-$length s$)1)$

$($string$-$contains s $"$y$")))$

$($define $($valid$-$whatzit? s$)$

$($and $(=($string$-$ref s $0)$ #$\backslash$q$)$

$(>($string$-$length s$)2)$

$($or $($string$-$contains s $"$z$")$

$($string$-$contains s $"$d$"))$

$($valid$-$blurb? $($substring s $2))))$

$($define $($valid$-$blurb? s$)$

$($cond $(($string$-$empty? s$)$ #t$)$

$(($valid$-$whoozit? s$)$

$($valid$-$blurb? $($substring s $($string$-$length $($match$0))))))$

$(($valid$-$whatzit? s$)$

$($valid$-$blurb? $($substring s $($string$-$length $($match$0))))))$

$($define $($main$)$

$($display "Enter an alien word: $")$

$($let loop $()$

$($let $(($input $($string$-$trim $($read$))))$

$($if $($valid$-$blurb? input$)$

$($display "The word is fine."$)$

$($begin

$($display "The word is a mess!"$)$

$($newline$)$

$($loop$))))))$

$($main$)$