old_contents: from django.contrib import admin
  from .models import CustomUser, Member
  from django.contrib.auth.admin import UserAdmin
  from django.contrib.auth.forms import UserChangeForm
  
  
  class CustomUserChangeForm(UserChangeForm):
      class Meta(UserChangeForm.Meta):
          model = CustomUser
  
  
  @admin.register(CustomUser)
  class CustomUserAdmin(UserAdmin):
      form = CustomUserChangeForm
  
      fieldsets = (
          (None, {'fields': ('email', 'password')}),
          ('Permissions', {'fields': ('is_active', 'is_superuser',
                                      'groups', 'user_permissions')}),
          ('Important dates', {'fields': ('last_login',)}),
      )
      add_fieldsets = (
          (None, {
              'classes': ('wide',),
              'fields': ('email', 'password1', 'password2'),
          }),
      )
      ordering = ('email',)
      list_display = ('email',)
      list_filter = ('is_superuser', 'is_active', 'groups')
      search_fields = ('email',)
  
  
  @admin.register(Member)
  class MemberAdmin(admin.ModelAdmin):
      list_display = ('get_full_name', 'created_at',)
      ordering = ('last_name', )
      search_fields = ('email', 'first_name', 'last_name', 'created_at')
  
new_contents: from django.contrib import admin
  from .models import CustomUser, Member
  from django.contrib.auth.admin import UserAdmin
  from django.contrib.auth.forms import UserChangeForm
  
  
  class CustomUserChangeForm(UserChangeForm):
      class Meta(UserChangeForm.Meta):
          model = CustomUser
  
  
  @admin.register(CustomUser)
  class CustomUserAdmin(UserAdmin):
      form = CustomUserChangeForm
  
      fieldsets = (
          (None, {'fields': ('email', 'password')}),
          ('Permissions', {'fields': ('is_active', 'is_superuser', 'is_admin', 'groups', 'user_permissions')}),
          ('Important dates', {'fields': ('last_login',)}),
      )
      add_fieldsets = (
          (None, {
              'classes': ('wide',),
              'fields': ('email', 'password1', 'password2'),
          }),
      )
      ordering = ('email',)
      list_display = ('email',)
      list_filter = ('is_superuser', 'is_active', 'groups')
      search_fields = ('email',)
  
  
  @admin.register(Member)
  class MemberAdmin(admin.ModelAdmin):
      list_display = ('get_full_name', 'created_at',)
      ordering = ('last_name', )
      search_fields = ('email', 'first_name', 'last_name', 'created_at')
  
subject: Add field. (#55)