def safewrap(value, arg):
    """
    Filter - replaces {0} in string with input variable
    Usage (in template):

    {% with link="connect.academy" %}
    {% with link_start='<a href="{0}">'|safewrap:link %}
    Results with the variable:
    link_start = <a href="connect.academy">
    """
    return value.format(arg)