def tags

      variables ? Hash[variables.select { |k, v| Ruote.is_a_fei?(v) }] : nil
    end
def tags

      variables ? Hash[variables.select { |k, v| Ruote.is_a_fei?(v) }] : nil
    end
Returns a hash tagname => fei of tags set at the root of the process
 instance.

 Returns nil if there is no defined root expression.