django admin源码阅读

	class ModelAdmin(BaseModelAdmin):
		...
		    def __init__(self, model, admin_site):
    			self.model = model
				# model例：<class 'django.contrib.auth.models.User'>
    			self.opts = model._meta
				# admin_site例：<django.contrib.admin.sites.AdminSite object at 0x2a5b150>
    			self.admin_site = admin_site 
    			super(ModelAdmin, self).__init__()