Django snippets

import datetime
from django import newforms as forms

class DateDropdownWidget(forms.MultiWidget):
    def __init__(self,attrs=None,year_range=None,month_range=None,day_range=None):
        YEARS = year_range or range(2000,2021)
        MONTHES = month_range or range(1,13)
        DAYS = day_range or range(1,32)

        years = map( lambda x: (x,x), YEARS )
        months = map(lambda x:(x,x), MONTHES )
        days = map( lambda x: (x,x), DAYS )

        widgets = (
                forms.Select(choices=years),
                forms.Select(choices=months),
                forms.Select(choices=days),
                )
        super(DateDropdownWidget, self).__init__(widgets, attrs)
    
    def format_output(self,widgets):
        format = "Year %s Month %s Day %s".decode('utf-8')
        return format%(widgets[0],widgets[1],widgets[2])

    def decompress(self,value):
        if value:
            return [value.year, value.month,value.day]
        return [None,None,None]

class DateField(forms.MultiValueField):
    widget = DateDropdownWidget
    def __init__(self,*args,**kwargs):
        fields = (
                forms.IntegerField( required=True),
                forms.IntegerField( required=True),
                forms.IntegerField( required=True ),
                )
        super(DateField, self).__init__(fields, *args,**kwargs )

    def compress(self,data_list):
        EMPTY_VALUES = [None, '']
        ERROR_EMPTY = "Fill the fields."
        ERROR_INVALID = "Enter a valid date."
        if data_list:
            if filter(lambda x: x in EMPTY_VALUES, data_list):
                raise forms.ValidationError(ERROR_EMPTY)
            
            try:
                return datetime.datetime(*map(lambda x:int(x),data_list))
            except ValueError:
                raise forms.ValidationError(ERROR_INVALID)
        return None