prefixes (REXML::Attributes)

    # File rexml/element.rb, line 1135
      def prefixes
    			ns = []
    			each_attribute do |attribute|
    				ns << attribute.name if attribute.prefix == "xmlns"
    			end
    			if @element.document and @element.document.doc_type
    				expn = @element.expanded_name
    				expn = @element.document.doc_type.name if expn.size == 0
    				@element.document.doc_type.attributes_of(expn).each {
    					|attribute|
    					ns << attribute.name if attribute.prefix == 'xmlns'
    				}
    			end
    			ns
    		end