def __init__(self, value, unit=None, delta_obj=None):
        """
        Args:
            value (float, str, dict) : Value of timedelta, string providing
                both unit and value, or a dictionary of units and times.
            unit (str) : Unit of time delta.
            delta_obj (pd.Timedelta or pd.DateOffset) : A time object used
                internally to do time operations. If None is provided, one will
                be created using the provided value and unit.
        """
        self.check_value(value, unit)
        self.times = self.fix_units()

        if delta_obj is not None:
            self.delta_obj = delta_obj
        else:
            self.delta_obj = self.get_unit_type()

        Args:
            value (float, str, dict) : Value of timedelta, string providing
                both unit and value, or a dictionary of units and times.
            unit (str) : Unit of time delta.
            delta_obj (pd.Timedelta or pd.DateOffset) : A time object used
                internally to do time operations. If None is provided, one will
                be created using the provided value and unit.
        
featuretools/entityset/timedelta.py