Iowa Code §§ 335.15 (counties) and 414.12 (cities) provide identical mandates for zoning boards of adjustment. These statutes are very specific in limiting the functions of the board of adjustment to (1) hearing appeals of decisions made by the zoning administrator, (2) granting or denying special exceptions (also referred to as “special uses” or “conditional uses”), and (3) granting or denying variances.