def each(options = {}, &block)
      options = {
        :source  => compares_files? ? 'files' : 'strings',
        :context => 3
      }.merge options
      Diffy::Diff.new(preprocessed_expected.to_s, preprocessed_produced.to_s, options).each &block
    end
def each(options = {}, &block)
      options = {
        :source  => compares_files? ? 'files' : 'strings',
        :context => 3
      }.merge options
      Diffy::Diff.new(preprocessed_expected.to_s, preprocessed_produced.to_s, options).each &block
    end
Enumerate all lines which differ.

 @param  [Hash] options
         see Diffy#initialize for help.

 @return [Diffy::Diff]