code: def get_samp_con():
      
  #
      samp_con, Z = "", ""
      while samp_con == "":
          samp_con = input("""
          Sample naming convention:
              [1] XXXXY: where XXXX is an arbitrary length site designation and Y
                  is the single character sample designation.  e.g., TG001a is the
                  first sample from site TG001.    [default]
              [2] XXXX-YY: YY sample from site XXXX (XXX, YY of arbitary length)
              [3] XXXX.YY: YY sample from site XXXX (XXX, YY of arbitary length)
              [4-Z] XXXX[YYY]:  YYY is sample designation with Z characters from site XXX
              [5] site name same as sample
              [6] site is entered under a separate column
              [7-Z] [XXXX]YYY:  XXXX is site designation with Z characters with sample name XXXXYYYY
              NB: all others you will have to customize your self
                   or e-mail ltauxe@ucsd.edu for help.
              select one:
  """)
      #
          if samp_con == "" or samp_con == "1":
              samp_con, Z = "1", 1
          if "4" in samp_con:
              if "-" not in samp_con:
                  print("option [4] must be in form 4-Z where Z is an integer")
                  samp_con = ""
              else:
                  Z = samp_con.split("-")[1]
                  samp_con = "4"
          if "7" in samp_con:
              if "-" not in samp_con:
                  print("option [7] must be in form 7-Z where Z is an integer")
                  samp_con = ""
              else:
                  Z = samp_con.split("-")[1]
                  samp_con = "7"
          if samp_con.isdigit() == False or int(samp_con) > 7:
              print("Try again\n ")
              samp_con = ""
      return samp_con, Z
docs: get sample naming  convention