gi cairo NoneType?

>>> from gi.repository import cairo
>>> foo = cairo.image_surface_create()
>>> type(foo)
<type 'NoneType'>
>>> cairo
<gi.module.DynamicModule 'cairo' from '/usr/lib64/girepository-1.0/cairo-1.0.typelib'>
>>>

~~~~~~~~~~~~

    <function name="image_surface_create" c:identifier="cairo_image_surface_create">
      <return-value transfer-ownership="none">
        <type name="none" c:type="void"/>
      </return-value>
      <parameters>
      </parameters>
    </function>