code: def add_sample_index_pdf(pdf, sample="sample_id"):
      pdf.index = ["id_" + str(index + 1) for index in pdf.index]
      pdf.index.name = "sample_id"
      pdf.index = pdf.index.map(str)
      return pdf
  
label_desc: Use image node_id 2 for calling a global function with example usage: add_sample_index_pdf(pdf, sample) and returns: pdf