nthe

class Event:

    def __init__(self):
        self._subscribers = set()

    @property
    def subscribers(self):
        return self._subscribers.copy()

nthe

class Allergen(models.Model):
    name = models.CharField(max_length=256, null=False, blank=False)

class Ingredient(models.Model):
    name = models.CharField(max_length=255, null=False, blank=False)
    description = models.TextField(null=True, blank=False)
    allergens = models.ManyToManyField(Allergen)                      # -> this fields creates table 
    may_contain = models.ManyToManyField(Extra)                       #    between Ingredient and Allergen
    

nthe

class Singleton(object):
    _instance = None

    def __new__(cls, *args, **kwargs):
        if not cls._instance:
            cls._instance = super(Singleton, cls).__new__(cls, *args, **kwargs)
        return cls._instance

nthe

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define fx for(i = 0; i < x; i++)
#define fy for(j = 0; j < y; j++)
#define nl printf("\n");
#define apc ap[j * x + i]
#define dc int i, j;