code: protected function compileMixins()
  	{
  		$sql = array();
  
  		foreach ($this->mixins as $mixin)
  		{
  			$compiled = $this->{$mixin}->compile();
  			if ($compiled !== "")
  			{
  				$sql[] = $compiled;
  			}
  		}
  
  		return $sql;
  	}
docs: Compiles all of the mixins into an array.
  
  @return array  All of the mixins into an array.