DB<138> @a=()

  DB<139> @a = (4..6) if !@a
 => (4, 5, 6)

  DB<140> @a=()

  DB<141>  @a  = @a ? @a : ( 1..6 ) ;
 => (1, 2, 3, 4, 5, 6)

  DB<142>  @a  = @a ? @a : ( 42 ) ;
 => (1, 2, 3, 4, 5, 6)

  DB<143> @a = (4..6) if !@a
 => ""

  DB<144> \@a
 => [1, 2, 3, 4, 5, 6]