RSpec Formatter Documentation with instant stack traces upon failure

.rspec

--colour
--backtrace
--require ./spec/support/documentation_instafail_formatter.rb
--format DocumentationInstafail

documentation_instafail_formatter.rb

require 'rspec/core/formatters/documentation_formatter'
require 'rspec/instafail'

class DocumentationInstafail < RSpec::Core::Formatters::DocumentationFormatter
  def example_failed(example)
    super(example)
    instafail.example_failed(example)
  end

  def instafail
    @instafail ||= RSpec::Instafail.new(output)
  end
end

This is awesome, thank you!