code: async function findInRoleMembership (fieldName, fieldValue, outputField, roleMembershipModel) {
    const results = await roleMembershipModel.find({
      where: {
        memberType: { equals: 'user' },
        [fieldName]: { equals: fieldValue }
      }
    })
    return results.map(r => r[outputField])
  }
docs: findUserIds / ////////////////////