# File lib/neo4jr-social/format_handler.rb, line 26
    def format(val=nil)
      unless val.nil?
       type = mime_type(val)
       fail "Unknown mime type #{val}\nTry registering the extension with a mime type" if type.nil?

       @format = val.to_sym
       response['Content-Type'].sub!(/^[^;]+/, type)
      end

      @format
    end