def switchport_pvlan_trunk_allowed_vlan
      return nil if switchport_mode == :disabled
      vlans = config_get('interface', 'switchport_pvlan_trunk_allowed_vlan',
                         name: @name)
      vlans = vlans.join(',') if vlans.is_a?(Array)
      vlans = Utils.normalize_range_array(vlans, :string) unless vlans == 'none'
      vlans
    end
def switchport_pvlan_trunk_allowed_vlan
      return nil if switchport_mode == :disabled
      vlans = config_get('interface', 'switchport_pvlan_trunk_allowed_vlan',
                         name: @name)
      vlans = vlans.join(',') if vlans.is_a?(Array)
      vlans = Utils.normalize_range_array(vlans, :string) unless vlans == 'none'
      vlans
    end
--------------------------
 <state> switchport private-vlan trunk allowed vlan <range>
 Note that range is handled as a string because the entire range is
 replaced instead of individually adding or removing vlans from the range.