code: def get_random_variant(df, seed=0):
      """
      returns a random chromosome, start position and sampleId for querying
      """
      row = df.sample(False, 0.1, seed=seed).limit(1).collect()
      chrom = row[0].contigName
      start = row[0].start
      sampleId = row[0].sampleId
      return chrom, start, sampleId
  
label_desc: Use image node_id 1 for calling a global function with example usage: get_random_variant(df, seed) and returns: chrom,  start,  sampleId