Python, This is how the homework statement looks like:  The Circle class takes Point object as the center of circle. To verify the center of the circle instance is a Point object, I added an if not isinstance() statement in __init__. This if statement raises TypeError when center is not a Point object. def __init__(self, center=(0,0), radius=1): 

 Point.__init__(self,center) self.center=center self.radius=radius if not isinstance(center,Point): raise TypeError("The center must be a Point!") 

 However, the code seems to accept any tuple in the form of (x,y) to be Point object. Is there a way to only pass the Point object to be center and anything else any tuple to be TypeError? This is what I am getting.  The following is the code for Point class import math class Point: def __init__(self,x=0,y=0): self.x = x self.y = y self.data=[x,y] def __getitem__(self, index): return self.data[index] def __iter__(self): yield self.x yield self.y def __add__(self,other): return Point(self.x+other.x,self.y+other.y) def __mul__(self,n): return Point(self.x*n,self.y*n) def __rmul__(self,n): return Point(n*self.x,n*self.y) @classmethod def from_tuple (cls, self=(0,0)): return cls(*self) def loc_from_tuple(self,t=(0,0)): self.x=t[0] self.y=t[1] def __str__(self): return "Point at ({0}, {1})".format(self.x,self.y) def __repr__(self): return"Point(x={0}, y={1})".format(self.x,self.y) 

The following is the code for Cirlce class:

class Circle(Point): def __init__(self, center=(0,0), radius=1): Point.__init__(self,center) self.center=center self.radius=radius if not isinstance(center,Point): raise TypeError("The center must be a Point!") def __getitem__(self,item): return self.center[item] def __str__(self): return "Circle with center at ({0}, {1}) and radius {2}".format(self.center.x, self.center.y, self.radius) def __repr__(self): return "Circle(center=Point({0}, {1}), radius {2})".format(self.center[0],self.center[1],self.radius) def __add__(self,other): return Circle( Point(self.center.x+other.center.x, self.center.y+other.center.y), self.radius+other.radius) @classmethod def from_tuple(cls, center,radius): return cls(center, radius) @property def radius(self): return self._radius @radius.setter def radius(self, radius): if radius  Your Circle class must define the creation order so it works like this without keywords: >>> circle= Circle(Point(1, 2), 2) >>circle Circle(center Point (1, 2), radius-2) >>> circle= Circle(1.5, Point(2, 3)) [This should raise an error that the center must be a Point; see below] Verify the center of the circle instance is a Point object and raise a TypeError if it isn't. This exception should happen on creation and modification. Hint: Use isinstance() >>> circle= Circle( center-4, radius=1.5) Traceback...] TypeError: The center must be a Point! >>> circle= Circle(center-Point (3,4), radius-2) >>> circle.center = (3, 4) Traceback...] TypeError: The center must be a Point