Assigns default values to multiple variables.
(a, b, c, ...)= defaultValues(x, y, z, ...)
{x, y, z, ...} The default values of {a, b, c, ...} .
{a, b, c, ...} If any of the outputs is undefined prior to the call, its value is set to the corresponding input. Otherwise its value value before the call is retained.

Any number of variables can be used on both sides. However, it is essential that the output arguments, even if there is only one, be enclosed in parentheses or square brackets.