old_contents: from django.contrib import admin
  from treebeard.admin import TreeAdmin
  from treebeard.forms import movenodeform_factory
  
  from .models import Account, Sheaf, Transaction, Document, Invoice
  
  
  class AccountAdmin(TreeAdmin):
      form = movenodeform_factory(Account)
  
  
  admin.site.register(Account, AccountAdmin)
  admin.site.register(Sheaf)
  admin.site.register(Transaction)
  admin.site.register(Document)
  admin.site.register(Invoice)
  
new_contents: from django.contrib import admin
  from treebeard.admin import TreeAdmin
  from treebeard.forms import movenodeform_factory
  
  from .models import Account, Sheaf, Transaction, Document, Invoice
  
  
  class AccountAdmin(TreeAdmin):
      form = movenodeform_factory(Account)
  
  admin.site.register(Account, AccountAdmin)
  
  
  class TransactionAdmin(admin.ModelAdmin):
      list_display = ('account', 'amount', 'currency', 'date')
  
  admin.site.register(Transaction, TransactionAdmin)
  
  
  class TransactionInline(admin.TabularInline):
      model = Transaction
      extra = 2
  
  
  class InvoiceAdmin(admin.ModelAdmin):
      list_display = ('timestamp', 'comment')
      inlines = (TransactionInline,)
  
  admin.site.register(Invoice, InvoiceAdmin)
  
  
  admin.site.register(Sheaf)
  admin.site.register(Document)
  
subject: improve admin