Declaring empty, non-NULL array in plpgsql

Is there a way to declare an array in plpgsql so that
it's empty (not NULL)? The following causes arr to end
up being NULL:

arr varchar[];
-- do stuff with arr..
arr = array_append(arr, '','');


And this causes an unwanted element at the front:

arr varchar[] := array[''''];
-- do stuff with arr..
arr = array_append(arr, '','');


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