docs: def get_genomic_seq_for_region(self, chrom, start_pos, end_pos):
          """ obtain the sequence for a genomic region
          """
          
          headers = {"content-type": "text/plain"}
          
          self.attempt = 0
          ext = "/sequence/region/human/{}:{}..{}:1".format(chrom, start_pos, end_pos)
          
          return self.ensembl_request(ext, headers)