Passing all tests except 'test_performer_detail_view'

from django.db import models

# Write your models here

class Performer(models.Model):
    name = models.CharField(max_length=255)

    def __str__(self):
        return '{}'.format(self.name)

class Song(models.Model):
    title = models.CharField(max_length=255)
    length = models.IntegerField(default=0)
    artist = models.CharField(max_length=255)
    performer = models.ForeignKey('Performer')

    def __str__(self):
        return  '{} by {}'.format(self.title, self.artist)

from django.shortcuts import get_object_or_404, render
from .models import Song, Performer
from django.http import HttpResponse

def performer_detail(request, pk):
  performer = get_object_or_404(Performer, pk=pk)
  return render(request, 'songs/performer_detail.html', {'performer': performer})

def song_list(request):
  songs = Song.objects.all()
  return render(request, 'songs/song_list.html', {'songs': songs})

def song_detail(request, pk):
  song = get_object_or_404(Song, pk=pk)
  return render(request, 'songs/song_detail.html', {'song': song})

{% extends 'base.html' %}

{% block title %}{{ performer.name }}{% endblock %}

{% block content %}
<section>
    {% for song in performer.song_set.all() %}
        <h3>{{ song.title }}</h3>
    {% endfor %}
</section>
{% endblock %}