What is the difference between __str__ and __repr__? — def __str__(self): - meant to be human readable def __repr__(self): - mean to represent the object and be unambiguous, usually as the constructor: for a Vector class, would be: def __repr__(self): return "Vector({!r}, {!r})".format(self.x, self.y) OR return "Vector(%r, %r)" % (self.x, self.y) Containers use __repr__ of elements when __str__ is called on container.