Wyo. Stat. Ann. § 15-6-433

If the city or town fails, neglects or refuses to pay the bonds or to promptly collect any assessment when due, the owner of any bonds may proceed in his own name to collect the assessments and foreclose the lien in any court of competent jurisdiction. The bondholder shall recover five percent (5%) in addition to the amount and interest thereon, together with the cost of the suit. Any number of holders of the bonds for any single improvement may join as plaintiffs, and any number of owners of property encumbered by the lien may be joined as defendants in the suit.