#Consider, however, what would happen if we turned the logic around: What if,

#instead of an @writable attribute, we had coded @read_only instead? The natural

#tendency would be to simply throw in a ! or a not:

  def title=( new_title )
    if not @read_only
      @title = new_title

  end
end

#The trouble with this if statement is that it is just slightly more verbose than

#it needs to be. A more concise—and idiomatic—way to say the same thing is:

  def title=( #new_title )
    unless @read_only
      @title = new_title
  end
end

#Olsen, Russ (2011). Eloquent Ruby (p. 18). Addison-Wesley Professional. Kindle #Edition.