code: def _non_excluded_alts(alts, exclude_alleles=None):
      """Exclude any alts listed, by default: '<*>', '.', and '<NON_REF>'.
  
      These alleles are sometimes listed in ALT column but they shouldn't be
      analyzed and usually indicate reference blocks in formats like gVCF.
  
      E.g. 'A'->'<*>' is NOT an insertion, and 'A'->'.' is NOT a SNP.
  
      Args:
        alts: a list of strings representing the alternate alleles.
        exclude_alleles: list(str). The alleles in this list will be ignored.
  
      Returns:
        alts alleles except those in exclude_alleles, by default excluding the GVCF
        '<*>' allele, the '<NON_REF>' symbolic allele, and '.' missing field by
        default.
      """
      if exclude_alleles is None:
          exclude_alleles = [
              vcf_constants.GVCF_ALT_ALLELE,
              vcf_constants.SYMBOLIC_ALT_ALLELE,
              vcf_constants.MISSING_FIELD,
          ]
      return [a for a in alts if a not in exclude_alleles]
  
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 9 for calling a global function with example usage: _non_excluded_alts(alts, exclude_alleles) and returns: unknown