text: """
  TR-specific Form helpers
  """
  
  from django.core.validators import EMPTY_VALUES
  from django.forms import ValidationError
  from django.forms.fields import Field, RegexField, Select, CharField
  from django.utils.encoding import smart_unicode
  from django.utils.translation import ugettext_lazy as _
  import re
  
  phone_digits_re = re.compile(r'^(\+90|0)? ?(([1-9]\d{2})|\([1-9]\d{2}\)) ?([2-9]\d{2} ?\d{2} ?\d{2})$')
  
  class TRPostalCodeField(RegexField):
      default_error_messages = {
          'invalid': _(u'Enter a postal code in the format XXXXX.'),
      }
  
      def __init__(self, max_length=5, min_length=5, *args, **kwargs):
          super(TRPostalCodeField, self).__init__(r'^\d{5}$',
              max_length, min_length, *args, **kwargs)
  
      def clean(self, value):
          value = super(TRPostalCodeField, self).clean(value)
          if value in EMPTY_VALUES:
              return u''
          if len(value) != 5:
              raise ValidationError(self.error_messages['invalid'])
          province_code = int(value[:2])
          if province_code == 0 or province_code > 81:
              raise ValidationError(self.error_messages['invalid'])
          return value
  
  
  class TRPhoneNumberField(CharField):
      default_error_messages = {
          'invalid': _(u'Phone numbers must be in 0XXX XXX XXXX format.'),
      }
  
      def clean(self, value):
          super(TRPhoneNumberField, self).clean(value)
          if value in EMPTY_VALUES:
              return u''
          value = re.sub('(\(|\)|\s+)', '', smart_unicode(value))
          m = phone_digits_re.search(value)
          if m:
              return u'%s%s' % (m.group(2), m.group(4))
          raise ValidationError(self.error_messages['invalid'])
  
  class TRIdentificationNumberField(Field):
      """
      A Turkey Identification Number number.
      See: http://tr.wikipedia.org/wiki/T%C3%BCrkiye_Cumhuriyeti_Kimlik_Numaras%C4%B1
  
      Checks the following rules to determine whether the number is valid:
  
          * The number is 11-digits.
          * First digit is not 0.
          * Conforms to the following two formula:
            (sum(1st, 3rd, 5th, 7th, 9th)*7 - sum(2nd,4th,6th,8th)) % 10 = 10th digit
            sum(1st to 10th) % 10 = 11th digit
      """
      default_error_messages = {
          'invalid': _(u'Enter a valid Turkish Identification number.'),
          'not_11': _(u'Turkish Identification number must be 11 digits.'),
      }
  
      def clean(self, value):
          super(TRIdentificationNumberField, self).clean(value)
          if value in EMPTY_VALUES:
              return u''
          if len(value) != 11:
              raise ValidationError(self.error_messages['not_11'])
          if not re.match(r'^\d{11}$', value):
              raise ValidationError(self.error_messages['invalid'])
          if int(value[0]) == 0:
              raise ValidationError(self.error_messages['invalid'])
          chksum = (sum([int(value[i]) for i in xrange(0,9,2)])*7-
                            sum([int(value[i]) for i in xrange(1,9,2)])) % 10
          if chksum != int(value[9]) or \
             (sum([int(value[i]) for i in xrange(10)]) % 10) != int(value[10]):
              raise ValidationError(self.error_messages['invalid'])
          return value
  
  class TRProvinceSelect(Select):
      """
      A Select widget that uses a list of provinces in Turkey as its choices.
      """
      def __init__(self, attrs=None):
          from tr_provinces import PROVINCE_CHOICES
          super(TRProvinceSelect, self).__init__(attrs, choices=PROVINCE_CHOICES)
  