Creating math formula in odf with odfpy

[Mich]

Hi!
Does anybody know how to insert math formula with odfpy? I am trying this

frame = odf.draw.Frame(relwidth = u"scalemin", relheight = u"scalemin",
anchortype = u"paragraph")
p = P()
doc.text.addElement(p)
obj = odf.draw.Object()
element = odf.math.Math()

# simple formula
element.addText(u'50 over 50')

obj.addElement(element)
frame.addElement(obj)
p.addElement(frame)

What is wrong?
Is there any documentation or samples?