code: def get_single_allele_from_reads(allele_reads):
      
      allele_reads = list(allele_reads)
  
      if len(allele_reads) == 0:
          raise ValueError("Expected non-empty list of AlleleRead objects")
  
      seq = allele_reads[0].allele
      if any(read.allele != seq for read in allele_reads):
          raise ValueError("Expected all AlleleRead objects to have same allele '%s', got %s" % (
              seq, allele_reads))
      return seq
docs: Given a sequence of AlleleRead objects, which are expected to all have
      the same allele, return that allele.