code: def from_hex(cls, h, space, assignment_class='self'):
          
  
          from math import log
  
          # Use the ln(N)/ln(base) trick to find the right number of hext digits
          # to  use
  
          hex_digits = int(
              round(log(62 ** TopNumber.DLEN.DATASET_CLASSES[assignment_class]) / log(16), 0))
  
          i = int(h[:hex_digits], 16)
  
          return TopNumber(space, i, assignment_class=assignment_class)
docs: Produce a TopNumber, with a length to match the given assignment
          class, based on an input hex string.
  
          This can be used to create TopNumbers from a hash of a string.