请严格以json格式回答：请解释一下XP模型。
user
```json
{
  "model": "XP",
  "full_name": "Extreme Programming",
  "description": "Extreme Programming (XP) is a software development methodology which is intended to improve software quality and responsiveness to changing customer requirements. XP promotes adaptive planning, evolutionary development, early delivery, and continuous improvement, and it encourages rapid and flexible response to change.",
  "key_practices": [
    "Pair programming",
    "Test-driven development",
    "Continuous integration",
    "Collective code ownership",
    "Refactoring",
    "Small releases",
    "Customer interaction",
    "Coding standards"
  ],
  "goals": [
    "Improve software quality",
    "Increase customer satisfaction",
    "Adapt to changing requirements",
    "Fast delivery of useful software"
  ]
}
```
assistant