docs: 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()