Sort dict by its keys

    >>> sort_dict_by_key(dict(c=1, b=2, a=3, d=4))
    OrderedDict([('a', 3), ('b', 2), ('c', 1), ('d', 4)])

def sort_dict_by_key(obj):
    """
    Sort dict by its keys

    >>> sort_dict_by_key(dict(c=1, b=2, a=3, d=4))
    OrderedDict([('a', 3), ('b', 2), ('c', 1), ('d', 4)])
    """
    sort_func = lambda x: x[0]
    return OrderedDict(sorted(obj.items(), key=sort_func))