def __init__(self):
        self.arg_index = 0
        self.arg_prefix = ''
        self.args = {}
        self.wheres = Q()
Return a preview from a mail's form's initial data.
dataset/ETHPy150Open ambitioninc/django-query-builder/querybuilder/query.py/Where.__init__--crossover with--dataset/ETHPy150Open novafloss/django-mail-factory/mail_factory/views.py/MailPreviewMixin.get_mail_preview