skew.py

def heap(el=None):
    return (el, None, None)
    
def union((el1, left1, right1), (el2, left2, right2)):
    if el1 is None: return (el2, left2, right2)
    if el2 is None: return (el1, left1, right1)
    if el1 < el2:
        return (el1, union((el2, left2, right2), right1), left1)
    else:
        return (el2, union((el1, left1, right1), right2), left2)

def insert(el, h):
    return union(heap(el), h)

def extract((el, left, right)):
    if el is None: return None, heap()
    return el, union(left, right)