( (square=.!arg^2)
& (1,3,5,7):?numbers
&     mop
    $ (square.!numbers.(=,).(=,))
  : ?squares2a
& out$!squares2a
&     mop
    $ ( (=.!arg^2)
      . !numbers
      . (=,)
      . (=,)
      )
  : ?squares2b
& out$!squares2b
& :?isquares1
&   whl
  ' ( !numbers:(?number,?numbers)
    & (!isquares1,!number^2):?isquares1
    )
& (!isquares1,!numbers^2):(,?isquares1)
& out$!isquares1
);