def fit_to(options={})
      self.fit_to_width = options[:width] || 999
      self.fit_to_height = options[:height] || 999
      [@fit_to_width, @fit_to_height]
    end
convenience method to achieve sanity when setting fit_to_width and fit_to_height
as they both default to 1 if only their counterpart is specified.
@note This method will overwrite any value you explicitly set via the fit_to_height or fit_to_width methods.
@option options [Integer] width The number of pages to fit this worksheet on horizontally. Default 999
@option options [Integer] height The number of pages to fit this worksheet on vertically. Default 999