( ( rep-string
  =   reps L x y
    .   ( reps
        =   x y z
          .   !arg:(?x.?y)
            & ( @(!y:!x ?z)&reps$(!x.!z)
              | @(!x:!y ?)
              )
        )
      & (   :?L
          & @( !arg
             :   %?x
                 !x
                 ( ?y
                 & reps$(!x.!y)
                 & !x !L:?L
                 & ~
                 )
             )
        |   !L:
          & out$(str$(!arg " is not a rep-string"))
        | out$(!arg ":" !L)
        )
  )
& rep-string$1001110011
& rep-string$1110111011
& rep-string$0010010010
& rep-string$1010101010
& rep-string$1111111111
& rep-string$0100101101
& rep-string$0100100
& rep-string$101
& rep-string$11
& rep-string$00
& rep-string$1
);