You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: api.rb
    path of file: ./repos/dd-trace-rb/lib/datadog/tracing/transport/http
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

require_relative '../../../core/encoding'

require_relative '../../../core/transport/http/api/map'
require_relative 'api/spec'

require_relative 'traces'

module Datadog
  module Tracing
    module Transport
      module HTTP
        # Namespace for API comp
    
          def defaults
            Datadog::Core::Transport::HTTP::API::Map[
              V4 => Spec.new do |s|
                s.traces = Traces::API::Endpoint.new(
                  '/v0.4/traces',
                  Core::Encoding::MsgpackEncoder,
                  service_rates: true
                )
              end,
              V3 => Spec.new do |s|
                s.traces = Traces::API::Endpoint.new(
                  '/v0.3/traces',
                  Core::Encoding::MsgpackEncoder
                )
              end,
            ].with_fallbacks(V4 => V3)
          end
        end
      end