Formal arguments of an
imported function can be specified as open arrays. A formal argument is an open
array when a range of one or more of its dimensions, packed or unpacked, is
unspecified (denoted by using empty square brackets
([])). An unpacked open array is a multi-dimensional dynamic array
formal and is thus denoted using the same syntax as dynamic arrays.
This is solely a relaxation of the argument-matching rules. An actual argument
shall match the formal one regardless of the range(s) for its corresponding
dimension(s), which facilitates writing generalized code that can handle
SystemVerilog arrays of different sizes. See Section 26.4.6.1.