def value_left ( self , other ) : return other . value if isinstance ( other , self . __class__ ) else other
python * left or right side
Returns the value of the other type instance to use in an operator method namely when the method s instance is on the left side of the expression .
def value_left(self, other):
    """
    Returns the value of the other type instance to use in an
    operator method, namely when the method's instance is on the
    left side of the expression.
    """
    return other.value if isinstance(other, self.__class__) else other