from random import random
from time import sleep
from functools import lru_cache



class Planet:
    """the nicest little orb this side of Orion's Belt"""

    GRAVITY_CONSTANT = 42
    TEMPORAL_SHIFT = 0.12345
    SOLAR_MASS_UNITS = 'M\N{SUN}'

    def __init__(self, color):
        self.color = color
        self._mass = None

    def __repr__(self):
        return f'{self.__class__.__name__}({repr(self.color)})'

    @property
    @lru_cache(maxsize=None)
    def mass(self):
        scale_factor = random()
        sleep(self.TEMPORAL_SHIFT)
        self._mass = (f'{round(scale_factor * self.GRAVITY_CONSTANT, 4)} '
                      f'{self.SOLAR_MASS_UNITS}')
        return self._mass