The SVGNumber interface corresponds to the <number> basic data type.
An SVGNumber object can be designated as read only, which means that attempts to modify the object will result in an exception being thrown.
SVGNumber.valueA float representing the number.
Note: If the SVGNumber is read-only, a DOMException with the code NO_MODIFICATION_ALLOWED_ERR is raised on an attempt to change the value.
This interface doesn't provide any specific methods.