from django.core.exceptions import ValidationError

class EmptyCheck(object):
    def __call__(self, value):
        if len(value.strip()) == 0:
            raise ValidationError("Value cannot be empty")

from django.core.exceptions import ValidationError

# Usage example in a custom form
# firstname = forms.CharField(validators = [EmptyCheck()])
class EmptyCheck(object):
    def __call__(self, value):
        if len(value.strip()) == 0:
            raise ValidationError("Value cannot be empty")

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