code: def hdr_xform(self, hdrs):
          
          xform = []
          hdrs = self.replace_nulls(hdrs)
          for hdr in hdrs:
              hdr = hdr.replace('.', '_')
              hdr = hdr.replace(' ', '_')
              hdr = hdr.replace('#', 'N')
              hdr = hdr.replace('-', '_')
              hdr = hdr.replace('"', '')
              xform.append(hdr)
          return xform
docs: Transform NCBI Gene header fields into valid namedtuple fields.