study for variable access

varAccess.py

class Var():
    x = "x"
    _x = "_x"
    __x = "__x"

    def __init__(self):
        self.y = "y"
        self._y = "_y"
        self.__y = "__y"

    def prAll(self):
#        print x, _x, __x # every variance evoke error
        print self.y, self._y, self.__y #no error

def prAllf(v):
#    print v.x, v._x, v.__x #v.__x evoke error
    print v.y, v._y, v.__y #v.__y evoke error

var = Var()
#prAllf(var) #__ cannot be accessed
#prAllf(Var()) #__ connot be accessed
var.prAll()
Var().prAll()


#print var._Var_x #error
print var._Var__x #no error

#print var._Var_y #error
print var._Var__y