code: function setAttribute($attr, $val, $compare = 'total', $case_sensitive = false) {
  		if ($val === null) {
  			return $this->deleteAttribute($attr, $compare, $case_sensitive);
  		}
  
  		$f = $this->findAttribute($attr, $compare, $case_sensitive);
  		if (is_array($f) && $f) {
  			foreach($f as $a) {
  				$this->attributes[$a[2]] = (string) $val;
  			}
  		} else {
  			$this->attributes[$attr] = (string) $val;
  		}
  	}
docs: Sets value(s) of attribute(s)
  @param string|int $attr Negative int to count from end
  @param string $compare Find node using "namespace", "name" or "total"
  @param bool $case_sensitive Compare with case sensitivity