Embedding and Using Custom Fonts with SASS

gistfile1.scss

/*
 * _mixins.scss
 */

$font_dir: '../fonts/';

/* _simple-font-url('Chunkfive', 'eot'); */
@function _simple-font-url($name, $extension)
{
    @return url($font_dir + $name + '-webfont.' + $extension);
}

/* _full-font-url('Chunkfive', 'woff', 'embedded-opentype', '?#iefix'); */
@function _full-font-url($name, $extension, $format, $hash: '')
{
    @return url($font_dir + $name + '/' + $name + '-webfont.' + $extension + $hash) format($format);
}

/* register-font('Chunkfive'); */
@mixin register-font($name)
{
    @font-face {
        font-family: $name;
        font-style: normal;
        font-weight: normal;
        src: _simple-font-url($name, 'eot');
        src: _full-font-url($name, 'woff', 'embedded-opentype', '?#iefix'),
             _full-font-url($name, 'ttf', 'truetype'),
             _full-font-url($name, 'svg', 'esvg', '?#' + $name);
	}
}

/*
prevent faux bold
http://www.alistapart.com/articles/say-no-to-faux-bold/
use-registered-font('Chunkfive');
*/
@mixin use-registered-font($name)
{
    font-family: $name, $sans-serif;
    font-weight: normal;
    letter-spacing: 0;
}

/*
 * sample_usage.scss
 */
@import "_mixins";

@include register-font('Chunkfive');

#logo
{
    @include use-registered-font('Chunkfive');
}

Think thats the typo. should be deleted or predefined on the top.