'WARNING: SortedDict() with ignore_case==True will
drop entries differing only in capitalisation!
Eg: SortedDict({\'auckland\':1, \'Auckland\':2}).keys() => [\'Auckland\']
With ignore_case==False it\'s all right'

def __init__(self, mapping={}, ignore_case=True, **kwargs):

    dict.__init__(self, mapping, **kwargs)
    self.ignore_case = ignore_case
