class Ougai::Formatters::Readable

def create_err_str(data)
  return nil unless data.key?(:err)
  err = data.delete(:err)
  err_str = "  #{err[:name]} (#{err[:message]}):"
  err_str += "\n" + (" " * @trace_indent) + err[:stack] if err.key?(:stack)
  err_str
end