code: def nan():
      d = ""
      if randrange(2):
          d = digits(randrange(99))
      if randrange(2):
          return "".join(("NaN", d))
      else:
          return "".join(("sNaN", d))
  
imports: from random import randrange, sample
  from fractions import Fraction
  from randfloat import un_randfloat, bin_randfloat, tern_randfloat
label_desc: Use image node_id 9 for calling a global function with example usage: nan() and returns: str, str