Hand of Straights

def isNStraightHand(hand, groupSize):
    if len(hand) % groupSize:
        return False
        
    count = {}
    for n in hand:
        count[n] = 1 + count.get(n, 0)
        
    minH = list(count.keys())
    heapq.heapify(minH)
    
    while minH:
        first = minH[0]
        for i in range(first, first + groupSize):
            if i not in count:
                return False
            count[i] -= 1
            if count[i] == 0:
                if i != minH[0]:
                    return False
                heapq.heappop(minH)
                
    return True