ri ljust

----------------------------------------------------------- String#ljust
     str.ljust(integer, padstr=' ')   => new_str
------------------------------------------------------------------------
     If _integer_ is greater than the length of _str_, returns a new
     +String+ of length _integer_ with _str_ left justified and padded
     with _padstr_; otherwise, returns _str_.

        "hello".ljust(4)            #=> "hello"
        "hello".ljust(20)           #=> "hello               "
        "hello".ljust(20, '1234')   #=> "hello123412341234123"