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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 get_single_value(value):
 """Get a single value out of the given value. This is meant to be used after a call to :func:`all_elements_equal` that returned True. With this function we return a single number from the input value. Args: value (ndarray or number):
 a numpy array or a single number. Returns: number: a single number from the input Raises: ValueError: if not all elements are equal """

    if not all_elements_equal(value):
        raise ValueError('Not all values are equal to each other.')

    if is_scalar(value):
        return value
    return value.item(0)