sass mixin breakpoint

1@mixin breakpoint($class) {  
2  @if $class == xs {    
3	@media (max-width: 767px) { @content; }  }   
4  @else if $class == sm {    
5    @media (min-width: 768px) { @content; }  }   
6  @else if $class == md {    
7    @media (min-width: 992px) { @content; }  }   
8  @else if $class == lg {    
9    @media (min-width: 1200px) { @content; }  }   
10  @else {    
11    @warn "Breakpoint mixin supports: xs, sm, md, lg";  
12  }
13}