Regex Pattern Generator & Explainer

Create and explain regular expression patterns.

**Task**: [DESCRIBE WHAT YOU WANT TO MATCH]

**Examples of valid inputs:**
- [EXAMPLE 1]
- [EXAMPLE 2]

**Examples of invalid inputs:**
- [EXAMPLE 1]
- [EXAMPLE 2]

**Generate:**

1. **Regex Pattern**
```
/pattern/flags
```

2. **Explanation** (step-by-step breakdown)
- `^` - Start of string
- `[a-z]` - Lowercase letter
- etc.

3. **Flags Explained**
- `g` - Global match
- `i` - Case insensitive
- `m` - Multiline

4. **Test Cases**
```
Should match:
✓ "example1"
✓ "example2"

Should not match:
✗ "invalid1"
✗ "invalid2"
```

5. **Code Examples**
- JavaScript
- Python
- PHP

6. **Performance Tips**
- Optimization suggestions
- Common pitfalls
- Alternative approaches