What am I doing wrong?

```
class Circle:
def __init__(self, m, r):
self.xm = m[0]
self.ym = m[1]
self.r = r
def __str__(self):
return "Circle"
def __contains__(self, point):
return True
```

In Sage:

```
sage: c = Circle((0,0),1)
sage: print (0,0) in c
TypeError: argument of type 'instance' is not iterable
```