# File lib/flowdock.rb, line 147
    def chat_message(params)
      raise InvalidParameterError, "missing api_token" if blank?(@api_token)
      raise InvalidParameterError, "Message must have :content" if blank?(params[:content])
      raise InvalidParameterError, "Message must have :flow" if blank?(params[:flow])
      params = params.clone
      tags = (params[:tags].kind_of?(Array)) ? params[:tags] : []
      params[:message] = params.delete(:message_id) if params[:message_id]
      tags.reject! { |tag| !tag.kind_of?(String) || blank?(tag) }
      event = if params[:message] then 'comment' else 'message' end
      post(event + 's', params.merge(tags: tags, event: event))
    end