In mako template: call python function within html string

How do I do this in mako:

<% import开发者_如何学编程 cherrypy %>
...
<link rel="stylesheet" href="${cherrypy.url('/media/layout.css')}" type="text/css" />

AttributeError: 'Undefined' object has no attribute 'url'

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Answer: Instead of <% import cherrypy %> one needs <%! import cherrypy %>