class Sass::Tree::Visitors::ToCss

def prepend!(prefix)
  @result.insert 0, prefix
  return unless @source_mapping
  line_delta = prefix.count("\n")
  offset_delta = prefix.gsub(/.*\n/, '').size
  @source_mapping.shift_output_offsets(offset_delta)
  @source_mapping.shift_output_lines(line_delta)
end