IndentationError：预期缩进的块（Django和Python）

Question

I'm currently working with Django on a proyect, when I'm about to import the models en the file models.py into the database this error shows up:

File "/home/hansen/Escritorio/SIDECO/sideco/models.py", line 31 class Empresa(models.Model): ^ IndentationError: expected an indented block

The code is the following:

   from django.db import models



class Sistema(models.Model):
   def lista_empresa():
       pass     
   def lista_desempleado():
       pass
   def dar_de_alta_desempleado():
       pass
   def dar_de_alta_empresa():
      pass
  def enviar_informacion_desempleado():
      pass
  def listado_desempleado(): 
      pass
  def almacenamiento_historico():
      pass

class Persona(models.Model): 
   DNI = models.CharField(max_length=10)
   tipo_de_trabajo = models.TextField()
   fecha_de_nacimiento = models.TextField()

class Empleado('Persona'):
   empresa = models.ForeignKey('Empresa')

class Desempleado('Persona'):

class Empresa(models.Model):
   cuil = models.CharField(max_length=12)
   razon_social = models.TextField()
   rubro = models.TextField()

    def contratar_desempleado():
        pass

class OfertaLaboral(models.Model):
   empresa = models.ForeignKey('Empresa')
   tipo_de_trabajo_solicitado = models.TextField()

Answer 1

you did not define the following class

class Desempleado('Persona'):

atleast try using pass as follows

class Desempleado('Persona'):
    pass