René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"New puzzle: Find a number with a number of 4s and 7s that has only 4s and 7s","articleBody":"```python\r\ndef sat(d: int):\r\n    \"\"\"\r\n    Find a number bigger than n whose decimal representation has k 4's and 7's where k's decimal representation\r\n    consists only of 4's and 7's\r\n\r\n    Inspired by [Codeforces Problem 110 A](https://codeforces.com/problemset/problem/110/A)\r\n    \"\"\"\r\n    return d \u003e 123456789 and set(str(str(d).count(\"4\") + str(d).count(\"7\"))) \u003c= {\"4\", \"7\"}\r\n```\r\n\r\nSolvers, post your solutions in the comments using the following formatting:\r\n````\r\n\u003cdetails\u003e\u003csummary\u003eReveal solution\u003c/summary\u003e\r\n\r\n```python\r\ndef sol():\r\n    return \"world\"  # replace with your solution\r\n```\r\n\u003c/details\u003e\r\n````\r\n","author":{"url":"https://github.com/akalai","@type":"Person","name":"akalai"},"datePublished":"2021-06-21T11:58:27.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/9/PythonProgrammingPuzzles/issues/9"}