code: function setAttributeNS($attr, $namespace, $compare = 'name', $case_sensitive = false) {
  		$f = $this->findAttribute($attr, $compare, $case_sensitive);
  		if (is_array($f) && $f) {
  			if ($namespace) {
  				$namespace .= ':';
  			}
  			foreach($f as $a) {
  				$val = $this->attributes[$a[2]];
  				unset($this->attributes[$a[2]]);
  				$this->attributes[$namespace.$a[1]] = $val;
  			}
  			$this->attributes_ns = null;
  			return true;
  		} else {
  			return false;
  		}
  	}
docs: Sets namespace of attribute(s)
  @param string|int $attr Negative int to count from end
  @param string $namespace
  @param string $compare Find node using "namespace", "name" or "total"
  @param bool $case_sensitive Compare with case sensitivity
  @return bool