How to add attributes in drupal 8 twig file?

Easy to use and to add attributes in drupal 8 twig file, here are some examples for attributes:
Add Class attributes..
Syntax: {{ attributes.addClass('myclass') }}
Example: <div {{ attributes.addClass('myclass') }}> <!-- any stuff here --> </div>
//here classes is the class name.
Remove Class attributes..
Syntax: {{ attributes.removeClass('myclass') }}

Example: <div {{ attributes.removeClass('myclass') }}> <!-- any stuff here --> </div>
here classes is the class name.
Add and Remove both attributes..
<div {{ attributes.addClass('myclass').removeClass('node') }}>

</div>
Add Multiple classes attribute..
{%
set classes = ['region','region-header']
%}
<div {{ attributes.addClass(classes)>
result: <div class="region region-header">

Add a setAttribute..
attributes.setAttribute($attribute, $value)
Syntax: <div{{ attributes.setAttribute('id', 'myID') }}></div>
Example: <div id="myID"></div>
 
Remove attributes..
attributes.removeAttribute($attribute)
Syntax: <div{{ attributes.removeAttribute('id') }}></div>

Check class exist or not..
attributes.hasClass($class)
Syntax:
{% if attributes.hasClass('myclass') %}
  {# here stuff #}
{% endif %}

Note: How to add attributes in drupal 8 twig file?