Unit formatting python OOP kata.

unit_formatter.py

#!/usr/bin/env python3
import math

class BaseFormatter(object):
    """
        Provides a generic formatting class.
        Just inherit from it, define your units,
        and then use pretty_format with any number.
    """

    @staticmethod
    def one_number_format(number, unit):
        unit_abbreviation = unit[0]
        return u"{:,}{}".format(number, unit_abbreviation)

    def __init__(self):
        if not hasattr(self, "units"):
            raise NotImplementedError("Please implement some units to handle")

    def pretty_format(self, number):
        current_number = number
        result = []

        for unit in self.units:
            limit = unit[1]
            if current_number > limit:
                reduced_number = current_number % limit
                result.append(self.one_number_format(reduced_number, unit))
                current_number = current_number // limit
            else:
                result.append(self.one_number_format(current_number, unit))
                break

        result.reverse()
        return " ".join(result)

class TimeFormatter(BaseFormatter):
    units = (
        ('ms', 1000),# Millisecond
        ('s', 60),   # Second
        ('m', 60),   # Minute
        ('h', 24),   # Hour
        ('d', 365),  # Day
        ('y', math.inf), # Year
    )

class DistanceFormatter(BaseFormatter):
    units = (
        ('mm', 10),
        ('cm', 100),
        ('m', 1000),
        ('km', 30856775800000),
        ('pc', math.inf),
    )

if __name__ == "__main__":
    FORMATTER1 = TimeFormatter()
    print("time:", FORMATTER1.pretty_format(1623956))

    FORMATTER2 = DistanceFormatter()
    print("distance:", FORMATTER2.pretty_format(67652345343528349039278))