This function is a template function that should be called
in 'HTML' templates before closing the "</body>"
tag.
Examples
back_top_button()
#> <div class="back-to-top">
#> <div class="btn-group dropup" role="group">
#> <a type="button" class="btn btn-default btn-go-top border-right-1" href="#">
#> <i class="fas fa-chevron-up" role="presentation" aria-label="chevron-up icon"></i>
#> </a>
#> <button type="button" class="btn btn-default dropdown-toggle dropdown-toggle-split border-left-1" data-toggle="dropdown" aria-haspopup="false" aria-expanded="false">
#> <span class="sr-only">Dropdown-Open</span>
#> </button>
#> <div class="dropdown-menu dropdown-menu-right">
#> <h6 class="dropdown-header">Jump to</h6>
#> </div>
#> </div>
#> </div>
back_top_button("rocket")
#> <div class="back-to-top">
#> <div class="btn-group dropup" role="group">
#> <a type="button" class="btn btn-default btn-go-top border-right-1" href="#">
#> <i class="fas fa-rocket" role="presentation" aria-label="rocket icon"></i>
#> </a>
#> <button type="button" class="btn btn-default dropdown-toggle dropdown-toggle-split border-left-1" data-toggle="dropdown" aria-haspopup="false" aria-expanded="false">
#> <span class="sr-only">Dropdown-Open</span>
#> </button>
#> <div class="dropdown-menu dropdown-menu-right">
#> <h6 class="dropdown-header">Jump to</h6>
#> </div>
#> </div>
#> </div>