lib/fit4ruby/FitMessageIdMapper.rb
def get_local(message)
      0.upto(15) do |i|
        if (entry = @entries[i]) && entry.global_message == message
          entry.last_use = Time.now
          return i
        end
      end
      nil
    end
def get_local(message)
      0.upto(15) do |i|
        if (entry = @entries[i]) && entry.global_message == message
          entry.last_use = Time.now
          return i
        end
      end
      nil
    end
Get the local message number for a given GlobalFitMessage. If there is
 no message number, nil is returned.