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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 random_sample(self, elements=('a', 'b', 'c'), length=None):
 """ Returns a list of random unique elements for the specified length. Multiple occurrences of the same value increase its probability to be in the output. """

        return self.random_elements(elements, length, unique=True)