code: def _get_training_data(vrn_files):
      
      out = {"SNP": [], "INDEL": []}
      # SNPs
      for name, train_info in [("train_hapmap", "known=false,training=true,truth=true,prior=15.0"),
                               ("train_omni", "known=false,training=true,truth=true,prior=12.0"),
                               ("train_1000g", "known=false,training=true,truth=false,prior=10.0"),
                               ("dbsnp", "known=true,training=false,truth=false,prior=2.0")]:
          if name not in vrn_files:
              return {}
          else:
              out["SNP"].append((name.replace("train_", ""), train_info, vrn_files[name]))
      # Indels
      if "train_indels" in vrn_files:
          out["INDEL"].append(("mills", "known=true,training=true,truth=true,prior=12.0",
                               vrn_files["train_indels"]))
      else:
          return {}
      return out
docs: Retrieve training data, returning an empty set of information if not available.