def audience(id)
      @url = "audiences/#{id}"
      raise OptimizelyError::NoAudienceID, "An Audience ID is required to retrieve the audience." if id.nil?

      response = self.get(@url)
      Audience.new(response)
    end
def audience(id)
      @url = "audiences/#{id}"
      raise OptimizelyError::NoAudienceID, "An Audience ID is required to retrieve the audience." if id.nil?

      response = self.get(@url)
      Audience.new(response)
    end
Returns the details for a specific audience.

 == Usage
  optimizely = Optimizely.new({ api_token: 'oauth2_token' })
  audience = optimizely.audience(12345) # Look up the audience.