code: def calc_an(variant):
      """Returns the total number of alleles in called genotypes in variant."""
      return sum(
          len([1 for gt in call.genotype if gt > -1])
          for call in variant.calls
      )
  
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 46 for calling a global function with example usage: calc_an(variant) and returns: sum