code: def count_unique_sequences(
          allele_reads,
          max_prefix_size=None,
          max_suffix_size=None):
      
      groups = group_unique_sequences(
          allele_reads,
          max_prefix_size=max_prefix_size,
          max_suffix_size=max_suffix_size)
      return {
          seq_tuple: len(read_names)
          for (seq_tuple, read_names) in groups.items()
      }
docs: Given a list of AlleleRead objects, extracts all unique
      (prefix, allele, suffix) sequences and associate each with the number
      of reads that contain that sequence.