# Learn Special Methods by Building a Vector Space - Step 29

### Tell us what’s happening:

Declare a variable args and assign it the value returned by joining the elements in arg_list with the string ‘, ‘.
def repr(self):
arg_list = [f’{key}={val}’ for key, val in vars(self).items()]
args=“,”.join(arg_list)

I may not understand the instructions but args=“,”.join(arg_list) is a join of the arglist and returns x=2,y=3

``````
class R2Vector:
def __init__(self, *, x, y):
self.x = x
self.y = y

def norm(self):
return sum(val**2 for val in vars(self).values())**0.5

def __str__(self):
return str(tuple(getattr(self, i) for i in vars(self)))

# User Editable Region

def __repr__(self):
arg_list = [f'{key}={val}' for key, val in vars(self).items()]
args=",".join(arg_list)
return args

# User Editable Region

class R3Vector(R2Vector):
def __init__(self, *, x, y, z):
super().__init__(x=x, y=y)
self.z = z

v1 = R2Vector(x=2, y=3)
v2 = R3Vector(x=2, y=2, z=3)
print(f'v1* = {v1.__repr__()}')
print(f'v2 = {v2}')
``````

User Agent is: `Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Safari/537.36`

### Challenge Information:

Learn Special Methods by Building a Vector Space - Step 29

sorry missing a space