APPEND and CONCAT functions accept multiple arguments

Now the APPEND function, which adds strings together, and the CONCAT function, which adds arrays together, can take more than two arguments.

This means that instead of writing:

APPEND("a", APPEND("b", "c"))
CONCAT([1, 2], CONCAT([3, 4], [5, 6])

You can now write:

APPEND("a", "b", "c")
CONCAT([1, 2], [3, 4], [5, 6])

Read the docs for multiple examples of applying these functions: APPEND and CONCAT