def fexp(fei)

      fei = Ruote.extract_fei(fei)

      @expressions.find { |e| e.fei == fei }
    end
def fexp(fei)

      fei = Ruote.extract_fei(fei)

      @expressions.find { |e| e.fei == fei }
    end
Given a fei, returns the flow expression with that fei (only looks
 in the expressions stored here, in this ProcessStatus instance, doesn't
 query the storage).