When using the Twig templating engine for PHP you might have used the trim filter to trim away any possible existing blanks at the beginning and end of a string:

{{ '  I like Twig.  '|trim }}

{# outputs 'I like Twig.' #}

Another way to trim out whitespaces is by using the – modifier:

<li>
    {{- value }}    </li>
{# outputs '<li>no spaces    </li>' #}