class Sass::SyntaxError

def modify_backtrace(attrs)
  attrs = attrs.reject {|k, v| v.nil?}
  # Move backwards through the backtrace
  (0...sass_backtrace.size).to_a.reverse.each do |i|
    entry = sass_backtrace[i]
    sass_backtrace[i] = attrs.merge(entry)
    attrs.reject! {|k, v| entry.include?(k)}
    break if attrs.empty?
  end
end