code: def variant_range_tuple(variant):
      """Returns a new tuple of (reference_name, start, end) for the variant.
  
      A common use case for this function is to sort variants by chromosomal
      location, with usage like `sorted(variants, key=variant_range_tuple)`.
  
      Args:
        variant: nucleus.genomics.v1.Variant.
  
      Returns:
        A three-tuple with the same reference_name, start, and end as variant.
      """
      return (variant.reference_name, variant.start, variant.end)
  
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 5 for calling a global function with example usage: variant_range_tuple(variant) and returns: variant,  variant,  variant