new_contents: import re
  
  from django import forms
  from django.utils.dateparse import parse_datetime
  from django.core.exceptions import ValidationError
  
  def valid_date(date):
      regex = ("^(?:[1-9]\d{3}-(?:(?:0[1-9]|1[0-2])-(?:0[1-9]|1\d|2[0-8])|(?:0[13"
               "-9]|1[0-2])-(?:29|30)|(?:0[13578]|1[02])-31)|(?:[1-9]\d(?:0[48]|["
               "2468][048]|[13579][26])|(?:[2468][048]|[13579][26])00)-02-29)T(?:"
               "[01]\d|2[0-3]):[0-5]\d:[0-5]\d(?:Z|[+-][01]\d:[0-5]\d)$")
      return re.search(regex, date)
  
  class VendDateTimeField(forms.DateTimeField):
      def to_python(self, value):
          if value not in self.empty_values and valid_date(value):
              try:
                  value = parse_datetime(value)
              except ValueError:
                  pass
          return super(VendDateTimeField, self).to_python(value)
  
subject: Create form field that can accept dates in the format used by the Vend API