def parse_outgoing_tokens(tokens)
      case tokens
      when NilClass
        []
      when String
        tokens.split(/[,\s]+/)
      when Array
        tokens
      end.to_set
    end
def parse_outgoing_tokens(tokens)
      case tokens
      when NilClass
        []
      when String
        tokens.split(/[,\s]+/)
      when Array
        tokens
      end.to_set
    end
use set of tokens for (more or less) O(1) lookup on multiple channels