code: def major_allele_frequency(variant):
      """Returns the frequency of the most common allele in the variant."""
      count_dict = collections.defaultdict(int)
      for call in variant.calls:
          for geno in call.genotype:
              count_dict[geno] += 1
      denom = sum(cnt for geno, cnt in count_dict.items() if geno >= 0)
      if denom > 0:
          numer = max(
              cnt for geno, cnt in count_dict.items() if geno >= 0
          )
          return float(numer) / denom
      else:
          return 0
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import collections
  import enum
  import itertools
  import six
  from third_party.nucleus.protos import variants_pb2
  from third_party.nucleus.util import ranges
  from third_party.nucleus.util import variantcall_utils
  from third_party.nucleus.util import vcf_constants
label_desc: Use image node_id 48 for calling a global function with example usage: major_allele_frequency(variant) and returns: unknown, int