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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 check_oneof(**kwargs):
 """Raise ValueError if more than one keyword argument is not none. Args: kwargs (dict):
 The keyword arguments sent to the function. Returns: None Raises: ValueError: If more than one entry in kwargs is not none. """

    # Sanity check: If no keyword arguments were sent, this is fine.
    if not kwargs:
        return None

    not_nones = [val for val in kwargs.values() if val is not None]
    if len(not_nones) > 1:
        raise ValueError('Only one of {fields} should be set.'.format(
            fields=', '.join(sorted(kwargs.keys())),
        ))