Bind First Argument

Create a decorator that fixes the first positional argument of a function.

decorators closures functions

Write a decorator `bind_first_arg` that takes a value `x` and returns a decorator. When applied to a function `f`, the decorated function should call `f` with `x` as the first positional argument, followed by any positional and keyword arguments passed to the decorated call. The function is defined as follows:

```python
def bind_first_arg(x):
    ...
```

The decorator should return a new function that, when called with `*args, **kwargs`, returns the result of `f(x, *args, **kwargs)`. The original function's behavior (including return value) should be preserved. You may assume `x` is given at decoration time and does not change.

For example, the following code should work:

```python
@bind_first_arg(1)
def add(a, b):
    return a + b
```

Then `add(2)` returns `3`. Similarly, after:

```python
@bind_first_arg(10)
def multiply(a, b, c):
    return a * b * c
```

`multiply(2, 3)` returns `60`. Also, you can bind built-in functions like `pow`: after `power = bind_first_arg(2)(pow)`, `power(3)` returns `8`.

Constraints

The decorated function can be called with any number of positional and keyword arguments. The function `f` can be any callable, including built-ins, lambdas, or user-defined functions. The implementation should not modify the original function or use global state. The solution must be correct for any number of arguments.

Example

>>> @bind_first_arg(1)
... def add(a, b):
...     return a + b
>>> add(2)
3
>>> @bind_first_arg(10)
... def multiply(a, b, c):
...     return a * b * c
>>> multiply(2, 3)
60
>>> power = bind_first_arg(2)(pow)
>>> power(3)
8

10 points ~15 min

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Hints

The outer function should return a decorator function.

The decorator should return a wrapper function that accepts *args and **kwargs.

Use a closure to capture x.

Call the original function with x passed first.

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