getValues() ). Including duplicates * gives us an efficient way to distinguish zero attributes from non-zero * but is not compliant with the spec, which states that duplicate * attributes must be removed. * * @return integer */ function count(); /** * Add any attributes in the argument to $this, but if an attribute of the * same name already exists, do not overwrite it. * * @param Attributes $other */ function merge( Attributes $other ); }