code: def variant_stats_from_variant(variant,
                                 metadata,
                                 merge_fn=(lambda all_stats: \
                                  max(all_stats, key=(lambda stats: stats.tumor_stats.depth)))):
      
      all_stats = []
      for (variant_file, variant_metadata) in metadata.items():
          if _vcf_is_maf(variant_file=variant_file):
              stats = maf_somatic_variant_stats(variant, variant_metadata)
          elif _vcf_is_strelka(variant_file=variant_file,
                               variant_metadata=variant_metadata):
              stats = strelka_somatic_variant_stats(variant, variant_metadata)
          elif _vcf_is_mutect(variant_file=variant_file,
                              variant_metadata=variant_metadata):
              stats = mutect_somatic_variant_stats(variant, variant_metadata)
          else:
              raise ValueError("Cannot parse sample fields, variant file {} is from an unsupported caller.".format(variant_file))
          all_stats.append(stats)
      return merge_fn(all_stats)
docs: Parse the variant calling stats from a variant called from multiple variant files. The stats are merged
      based on `merge_fn`
  
      Parameters
      ----------
      variant : varcode.Variant
      metadata : dict
          Dictionary of variant file to variant calling metadata from that file
      merge_fn : function
          Function from list of SomaticVariantStats to single SomaticVariantStats.
          This is used if a variant is called by multiple callers or appears in multiple VCFs.
          By default, this uses the data from the caller that had a higher tumor depth.
  
      Returns
      -------
      SomaticVariantStats