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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 context_chunk(self, context, j):
 """ Retrieve the tokens in the ``j``th chunk of context ``context``. Parameters context : str Context name. j : int Index of a context chunk. Returns ------- chunk : list List of tokens in the selected chunk. """


        N_chunks = len(self.contexts[context])
        start = self.contexts[context][j]
        if j == N_chunks - 1:
            end = len(self)
        else:
            end = self.contexts[context][j+1]
        return [self[i] for i in xrange(start, end)]