def __init__(self, field=None, table=None, alias=None, cast=None, distinct=None, over=None, offset=1, default=None):
        super(LeadLagField, self).__init__(field, table, alias, cast, distinct, over)
        self.offset = offset
        self.default = default
Sets the offset and default value for the lag/lead calculation
dataset/ETHPy150Open ambitioninc/django-query-builder/querybuilder/fields.py/LeadLagField.__init__