The property value will always be returned if the key is provided (whether a value is provided or not).
An associative array if no property key is specified.
Gets or sets the attributes stored inside this image object, which are used to output HTML attributes. These attributes may be populated by calling this method, or are populated by the image field type in the MasterPress UI. Importantly, these attributes are also passed through to any resizing or filtering methods, so that titles and alt attributes will be preserved when outputting tags after any processing occurs.
The name of the attrbibute to set or retrieve. If this value is empty, the entire set of attributes is returned as an associative array.
Mixed $val = null
If you wish to set a property on this image, specify the value here.