Return First and Last Parameter

Write two functions:

1. first_arg() should return the first parameter passed in.
2. last_arg() should return the last parameter passed in.

Examples

first_arg(1, 2, 3) ➞ 1

last_arg(1, 2, 3) ➞ 3

first_arg(8) ➞ 8

last_arg(8) ➞ 8

Notes

• Return None if the function takes no parameters.
• If the function only takes in one parameter, the first_arg and last_arg functions should return the same value.