Error !

TypeError: 'Undefined' object is not iterable

49
<%def name="teachers()">
50
<select style="width:70%;" id="ac_teacher" name="teacher" data-placeholder="${_('Dozent suchen')}">
51
<option></option>
52
		% for teacher in teachersjson:
53
<option value="${teacher['id']}">${teacher['text']}</option>
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		% endfor
55
</select>
56
				<noscript>
57
						<input type="submit" value="Suche">
/var/www/vlvz.py/vlvz/templates/autocompleteHTML.mako, line 52:
52
		% for teacher in teachersjson:
/var/www/vlvz.py/vlvz/templates/filter.mako, line 192:
192
    ${autocompleteHTML.teachers()}
/usr/lib/python2.7/dist-packages/mako/runtime.py, line 761:
761
callable_(ctx, **kwargs)
/var/www/vlvz.py/vlvz/templates/lehrangebot.mako, line 27:
27
     <%include file="/filter.mako"/>
/var/www/vlvz.py/vlvz/templates/base.mako, line 286:
286
				${self.filter()}
/usr/lib/python2.7/dist-packages/mako/runtime.py, line 899:
899
callable_(context, *args, **kwargs)
/usr/lib/python2.7/dist-packages/mako/runtime.py, line 873:
873
_exec_template(inherit, lclcontext, args=args, kwargs=kwargs)
/usr/lib/python2.7/dist-packages/mako/runtime.py, line 838:
838
**_kwargs_for_callable(callable_, data))
/usr/lib/python2.7/dist-packages/mako/template.py, line 462:
462
return runtime._render(self, self.callable_, args, data)
/var/www/vlvz.py/vlvz/webvlvz2.py, line 333:
333
return tpl.render(**data)