Could you explain how following code would execute and at which line object is created for class and how methods are called ?

Question

def reverse_numeric(x, y):
return y - x
def cmp_to_key(mycmp):
'Convert a cmp= function into a key= function'
class K:
def __init__(self, obj, *args):
self.obj = obj
def __lt__(self, other):
return mycmp(self.obj[1], other.obj[1]) < 0
return K
print(sorted([[1,2], [2,4], [3,6]], key=cmp_to_key(reverse_numeric)))