Add args to Jinja filters

[eitanturok]

In the outlines docs, we have the example

import outlines

def my_tool(arg1: str, arg2: int):
    """Tool description.

    The rest of the docstring
    """
    pass

@outlines.prompt
def tool_prompt(question, tool):
    """{{ question }}

    COMMANDS
    1. {{ tool | name }}: {{ tool | description }}, args: {{ tool | args }}

    {{ tool | source }}
    """

prompt = tool_prompt("Can you do something?", my_tool)
print(prompt)

However, when I tried running this code, it did not work because the args filter used in {{ tool | args }} was not implemented. I implemented the args filter so now this example works.

Now the args filter will output all of the arguments with the type annotations and default values (if they are provided).
Example:

from typing import List

def foo(x, y: str, z: List[int]=[1, 2, 3]):
    pass

@outlines.prompt
def tool_prompt(fn):
    """My args: {{ fn | args }}"""

prompt = tool_prompt(foo)
print(prompt)

which outputs

My args: x, y: str, z: List[int] = [1, 2, 3]

[rlouf]

Thank you so much for contributing!