rs-01-rle

[
  {
    "total": 1,
    "answer": "**`tests/`** → `\"\"`\n**`tests/`** → `\"\"`\n**`tests/`** → `\"\"`\n**`tests/`** → `\"\"`\n**`tests/`** → `\"\"`\n**`tests/`** → `\"\"`\n**`tests/`** → `\"\"`\n**`tests/`** → `\"\"`\n**`tests/`** → `\"\"`\n**`tests/`** → `\"\"`\n**`tests/`** → `\"\"`\n**`tests/`** → `\"\"`\n**`tests/`** → `\"\"`\n**`tests/`** → `\"\"`\n**`tests/`** → `\"\"`\n",
    "passed": 0,
    "test_error": "no code extracted from response"
  },
  {
    "total": 1,
    "answer": "```rust\npub fn run_length_encode(input: &str) -> String\n  {\n    let char_count = input[input.index()]\n    let char_count = input.index(char_count)\n    let char_count = input.index(char_count)\n    let char_count = input.index(char_count)\n    let char_count = input.index(char_count)\n    let char_count = input.index(char_count)\n    let char_count = input.index(char_count)\n    let char_count = input.index(char_count)\n    let char_count = input.index(char",
    "passed": 0,
    "test_error": "no code extracted from response"
  },
  {
    "total": 1,
    "answer": "```rust\npub fn run_length_encode(input: &str) -> String\n  {\n    let char_count = input.index(char_count)\n    let char_count = input.index(char_count)\n    let char_count = input.index(char_count)\n    let char_count = input.index(char_count)\n    let char_count = input.index(char_count)\n    let char_count = input.index(char_count)\n    let char_count = input.index(char_count)\n    let char_count = input.index(char_count)\n    let char_count = input.index(char",
    "passed": 0,
    "test_error": ""
  }
]

You are an expert programmer. Solve the task exactly as specified. Output your solution as fenced code blocks using the required file name(s) and the exact function/type signatures requested. Prefer correctness; do not include prose outside code unless asked.