code: def get_age(dob: PotentialDatetimeType,
              when: PotentialDatetimeType,
              default: str = "") -> Union[int, str]:
      
      dob = coerce_to_pendulum_date(dob)
      when = coerce_to_pendulum_date(when)
      if dob is None or when is None:
          return default
      return (when - dob).years
docs: Age (in whole years) at a particular date, or ``default``.
  
      Args:
          dob: date of birth
          when: date/time at which to calculate age
          default: value to return if either input is ``None``
  
      Returns:
          age in whole years (rounded down), or ``default``