you don't have to merely trust; it's documented in perldata:

You may have an optional comma before the closing parenthesis of a list literal

In fact, you can have extra commas anywhere you want in a list except (for reasons I can't explain) at the very front of it. They will not cause undef items to be created, nor will including nested empty lists.

my @items = ((),,,,5);
print "<$_>\n" for @items;
# prints only one item
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