@stof thanks for the tip, I'll fix it. I was taking a look at the `_getBooleanAttribute` implementation and I have some questions, maybe you could help me out:

http://www.w3.org/TR/2004/REC-xmlschema-2-20041028/datatypes.html#boolean

From what I make out of the specification, we should also allow `some-attr='1'` to return true.
Also, using `some-attr='fish'` will return false, when it probably should throw an exception.