The following code takes a fixnum and transforms it to a string. 
If the fixnum is a one digit number, a prefix will be added. The 
code is useful to display numbers in a "digital clock" way.

  def format_to_2digits (no)
    # Precondition: no.type == Fixnum
    str = no.to_s
    str[0, 0] = "0" if str.size == 1 else str
  end

The last line of the method is a bit strange but the code works
fine (I was just experimenting). But while executing the code
I got the following warning from the interpreter:

  test.rb:74: warning: else without rescue is useless

Is there something wrong with my code? Or is this a bug?


My Ruby version in case this is relevant:

  ruby 1.6.2 (2000-11-04) [i386-mingw32]
  

Regards,
Paul.