--- breakable([sep[, width]])
#    tells "you can break a line here if necessary", and a
#    width-column text sep is inserted if a line is not
#    broken at the point.
    ɬפʤ餳ǲԽפȤȤΤޤ
    ⤷ΰ֤ǲԤʤС
    widthΥƥ sep ޤ

#    If sep is not specified, " " is used.
    sep ꤵʤ " " Ѥޤ

#    If width is not specified, sep.length is used.
#    You will have to specify this when sep is a multibyte
#    character, for example.
    width ꤵʤСsep.length Ѥޤ
    㤨 sep ¿Хʸκݤ˻ꤹɬפ뤫Τޤ

