The conversation between human and AI assistant.
[|Human|] Edit the given HTML code so that it can be used as login form.
[|AI|] Here is the edited HTML code for a login form: 

<form>
  <label for="username">Username:</label>
  <input type="text" id="username" name="username" size="20"><br><br>
  <label for="password">Password:</label>
  <input type="password" id="password" name="password" size="20"><br><br>
  <input type="submit" value="Submit">
</form>
[|Human|] 
Edit the given HTML code so that it can be used as login form.