code: def phased_genotypes_to_haplotypes(
      variants_and_genotypes, start, ref
  ):
      """Returns a map from phased genotypes => haplotype sequences.
  
      This function creates a map from all possible haploid genotypes of the
      genotypes in variants_and_genotypes to their corresponding haplotype sequences
      implied by the variants, ref, start, and their genotypes. This map can be used
      to efficiently look up the haplotype sequence for any haploid genotype.
  
      Args:
        variants_and_genotypes: list[VariantAndGenotypes]. The variants and
          associated genotypes to use to build the dictionary.
        start: int >= 0. The position on the genome to start constructing our
          haplotypes at.
        ref: ReferenceRegion. Object containing the reference genome bases we use to
          construct our haplotypes.
  
      Returns:
        A 2-tuple. The first element is a dictionary[tuple, string], where each key
        is a phased haploid genotype and its value is the haplotype sequence implied
        by that genotype given the variants and the reference genome. The second
        position is the ending position of the haplotype on the reference genome.
      """
      genotypes_to_haplotypes = {}
      genotypes = [vg.genotypes for vg in variants_and_genotypes]
      variants = [vg.variant for vg in variants_and_genotypes]
      all_haploid_genotypes = sorted(set(itertools.product(*genotypes)))
      end = max(v.end for v in variants)
      for phased in all_haploid_genotypes:
          haplotype = build_haplotype(variants, phased, ref, start, end)
          if haplotype:
              genotypes_to_haplotypes[phased] = haplotype
      return genotypes_to_haplotypes, end
  
imports: import collections
  import copy
  import enum
  import heapq
  import itertools
  from absl import logging
  from deepvariant.labeler import variant_labeler
  from deepvariant.protos import deepvariant_pb2
  from third_party.nucleus.io import fasta
  from third_party.nucleus.util import ranges
  from third_party.nucleus.util import variant_utils
  from third_party.nucleus.util import variantcall_utils
label_desc: Use image node_id 9 for calling a global function with example usage: phased_genotypes_to_haplotypes(variants_and_genotypes, start, ref) and returns: genotypes_to_haplotypes,  end