docs: def number_of_decimals(num):
      r"""
      Args:
          num (float):
  
      References:
          stackoverflow.com/questions/6189956/finding-decimal-places
  
      Example:
          >>> # ENABLE_DOCTEST
          >>> from utool.util_alg import *  # NOQA
          >>> num = 15.05
          >>> result = number_of_decimals(num)
          >>> print(result)
          2
      """
      exp = decimal.Decimal(str(num)).as_tuple().exponent
      return max(0, -exp)