code: def un_close_to_pow10(prec, maxexp, itr=None):
      if itr is None:
          lst = range(prec + 30)
      else:
          lst = sample(range(prec + 30), itr)
      nines = [10**n - 1 for n in lst]
      pow10 = [10**n for n in lst]
      for coeff in nines:
          yield coeff
          yield -coeff
          yield from_triple(1, coeff, randrange(2 * maxexp))
          yield from_triple(-1, coeff, randrange(2 * maxexp))
      for coeff in pow10:
          yield coeff
          yield -coeff
  
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 17 for calling a global function with example usage: un_close_to_pow10(prec, maxexp, itr) without return types