'Get the definition for the property I{name}.
@param name: The property I{name} to find the definition for.
@type name: str
@return: The property definition
@rtype: L{Definition}
@raise AttributeError: On not found.'

def definition(self, name):

    d = self.definitions.get(name)
    if (d is None):
        raise AttributeError(name)
    return d
