input: Write a python function to create a bar chart of the number of completed todos for each user from a given API endpoint.
  assert create_completed_todos_chart('https://jsonplaceholder.typicode.com/todos') is None
output: import requests
  import matplotlib.pyplot as plt
  
  def create_completed_todos_chart(api_url):
      response = requests.get(api_url)
      todos = response.json()
  
      user_completed_counts = {}
      
      for todo in todos:
          if todo['completed']:
              user_id = todo['userId']
              if user_id in user_completed_counts:
                  user_completed_counts[user_id] += 1
              else:
                  user_completed_counts[user_id] = 1
  
      users = list(user_completed_counts.keys())
      completed_counts = list(user_completed_counts.values())
  
      plt.bar(users, completed_counts)
      plt.xlabel('User ID')
      plt.ylabel('Number of Completed Todos')
      plt.title('Number of Completed Todos by User')
      plt.show()