§ 240.10  Unlawful assembly.
  A  person  is  guilty of unlawful assembly when he assembles with four or
more other persons for the purpose of engaging or preparing to engage  with
them  in  tumultuous  and  violent conduct likely to cause public alarm, or
when, being present at an  assembly  which  either  has  or  develops  such
purpose, he remains there with intent to advance that purpose.
  Unlawful assembly is a class B misdemeanor.