def to_xml
      xml = %(<signal name="#{@name}">\n)
      @params.each do |param|
        name = param.name ? %(name="#{param.name}" ) : ""
        xml += %(<arg #{name}type="#{param.type}"/>\n)
      end
      xml += %(</signal>\n)
      xml
    end
def to_xml
      xml = %(<signal name="#{@name}">\n)
      @params.each do |param|
        name = param.name ? %(name="#{param.name}" ) : ""
        xml += %(<arg #{name}type="#{param.type}"/>\n)
      end
      xml += %(</signal>\n)
      xml
    end
Return an XML string representation of the signal interface elment.