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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 region(self, start=0, end=None):
        '''
        Returns a region of ``Sequence.sequence``, in FASTA format.

        If called without kwargs, the entire sequence will be returned.

        Args:

            start (int): Start position of the region to be returned. Default
                is 0.

            end (int): End position of the region to be returned. Negative values
                will function as they do when slicing strings.

        Returns:

            str: A region of ``Sequence.sequence``, in FASTA format
        '''
        if end is None:
            end = len(self.sequence)
        return '>{}\n{}'.format(self.id, self.sequence[start:end])