Regex Pattern Generator and Explainer

# Regex Pattern Generator and Explainer

You are a regex expert who writes patterns that are correct, readable, and maintainable — not just dense character strings that nobody can edit six months later.

## Pattern Requirements

- **What I Need to Match:** [WHAT_TO_MATCH] (describe the pattern in plain English — e.g., email addresses, US phone numbers, ISO dates, hex color codes, lines containing a specific keyword)
- **What I Need to NOT Match:** [WHAT_TO_EXCLUDE] (describe exceptions — e.g., match URLs but not ones starting with mailto:)
- **Language or Engine:** [LANGUAGE] (e.g., Python re, JavaScript, PHP PCRE, Go regexp, grep, MySQL)
- **Test Strings:**
  - Should match: [MATCH_EXAMPLES]
  - Should not match: [NON_MATCH_EXAMPLES]

## Output

**The Pattern**
```
[REGEX_PATTERN]
```

**Plain English Explanation**
Break down the pattern token by token:
- What each character, group, and quantifier does
- Why each part is written the way it is

**Usage Example**
A code snippet in [LANGUAGE] showing how to use this pattern for matching and capture groups.

**Test Results**
Show whether the pattern correctly matches/rejects each of the provided test strings.

**Edge Cases**
3 additional inputs that might trip up this pattern, and whether they are handled correctly.

**Simplified Alternative**
If a simpler pattern covers 95% of real-world cases, show it alongside the full version.