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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def key_from_dict(**kwargs):
 """ Return a unique string representation of a dict as quickly as possible. Used to generated deduplication keys from a request. """

    out = []
    stack = [kwargs]
    while stack:
        obj = stack.pop()
        if isinstance(obj, dict):
            stack.extend(sorted(obj.items()))
        elif isinstance(obj, (list, tuple)):
            stack.extend(obj)
        else:
            out.append(str(obj))
    return ''.join(out)