super(key, ...callArgs) {
				if (key == null)
					return null;

				const slotIdx = `${this.__id__}.${key}`;
				const symStack = superContext[slotIdx];
				let protoCtx = null;

				for (protoCtx = Object.getPrototypeOf(symStack ? symStack[0] : Object.getPrototypeOf(this));
					 protoCtx != null && !protoCtx.hasOwnProperty(key);
					 protoCtx = Object.getPrototypeOf(protoCtx)) {}

				if (protoCtx == null)
					return null;

				let res = protoCtx[key];

				if (callArgs.length > 0) {
					if (typeof(res) != 'function')
						throw new ReferenceError(`${key} is not a function in base class`);

					if (Array.isArray(callArgs[0]) || LuCI.prototype.isArguments(callArgs[0]))
						callArgs = callArgs[0];

					if (symStack)
						symStack.unshift(protoCtx);
					else
						superContext[slotIdx] = [ protoCtx ];

					res = res.apply(this, callArgs);

					if (symStack && symStack.length > 1)
						symStack.shift(protoCtx);
					else
						delete superContext[slotIdx];
				}

				return res;
			}
Walks up the parent class chain and looks for a class member
called `key` in any of the parent classes this class inherits
from. Returns the member value of the superclass or calls the
member as function and returns its return value when the
optional `callArgs` array is given.

This function has two signatures and is sensitive to the
amount of arguments passed to it:
 - `super('key')` -
	Returns the value of `key` when found within one of the
	parent classes.
 - `super('key', ['arg1', 'arg2'])` -
	Calls the `key()` method with parameters `arg1` and `arg2`
	when found within one of the parent classes.

@memberof LuCI.baseclass
@instance

@param {string} key
The name of the superclass member to retrieve.

@param {Array<*>} [callArgs]
An optional array of function call parameters to use. When
this parameter is specified, the found member value is called
as function using the values of this array as arguments.

@throws {ReferenceError}
Throws a `ReferenceError` when `callArgs` are specified and
the found member named by `key` is not a function value.

@returns {*|null}
Returns the value of the found member or the return value of
the call to the found method. Returns `null` when no member
was found in the parent class chain or when the call to the
superclass method returned `null`.