What is the `functools.singledispatch` decorator?

Question

Accepted Answer

**singledispatch** — generic function based on first argument type.

```python
from functools import singledispatch

@singledispatch
def process(data):
    raise TypeError(f"Unsupported type: {type(data)}")

@process.register(int)
_(data):
    return f"Integer: {data * 2}"

@process.register(str)
_(data):
    return f"String: {data.upper()}"

@process.register(list)
_(data):
    return f"List of {len(data)} items"

print(process(42))       # Integer: 84
print(process("hello"))  # String: HELLO
print(process([1, 2, 3]))  # List of 3 items
```

**Use cases:**
- Serialization (JSON, XML).
- Type-specific processing.
- Plugin systems.

Python: What is the `functools.singledispatch` decorator?