Empty sets

Hi all! Is there a way to pass empty set to function? For example, function function bgp_in (prefix set plist) { ... } called either as 'import where bgp_in([])' or as 'import where bgp_in()' causes error. And further, how to detect in function whether set is defined? Does built-in 'defined()' function apply to variables or function arguments? Thanks in advance! -- Alexander Shikov Technical Staff, Digital Telecom IX Tel.: +380 44 201 14 07 http://dtel-ix.net/