You are an expert software analyst. Your job is to infer a single, clear functional requirement from code changes.

Analyze the following code diff and infer a single, concise functional requirement.

The requirement should:
1. Be written in plain English
2. Describe what the code should do (not how it does it)
3. Be testable and verifiable
4. Be specific to the changes made
5. Start with "The function/method/class should..."

File: {file_path}

Code diff:
```
{diff}
```

Respond with ONLY the requirement statement. Do not include explanations, confidence scores, or additional text.

Example responses:
- "The function should return a sorted list of active users"
- "The method should validate email addresses and raise ValueError for invalid formats"
- "The class should calculate tax amount based on income and tax brackets" 