Creates a BED/GFF file of the 5' end of each feature represented in the
        table and returns the resulting pybedtools.BedTool object. Needs an
        attached database.

        Parameters
        ----------
        upstream, downstream : int
            Number of basepairs up and downstream to include

def five_prime(self, upstream=1, downstream=0):
        """
        Creates a BED/GFF file of the 5' end of each feature represented in the
        table and returns the resulting pybedtools.BedTool object. Needs an
        attached database.

        Parameters
        ----------
        upstream, downstream : int
            Number of basepairs up and downstream to include
        """
        return pybedtools.BedTool(self.features())\
            .each(featurefuncs.five_prime, upstream, downstream)\
            .saveas()