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  Question 1: Valid Python Variable Name Checker
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FULL QUESTION:
Check whether the given string can be used as a valid variable name in Python.

Explanation:
In Python, a valid variable name:
- Can only contain letters (a-z, A-Z), digits (0-9), and underscores (_).
- The variable name cannot begin with a digit.
- The string cannot contain reserved keywords such as "for", "if", "class", etc.

SHORT QUESTION:
Validates if a user-supplied string is a valid Python variable name and not a reserved keyword.

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README & SETUP INSTRUCTIONS:
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# Question 1: Valid Python Variable Name Checker

- Prerequisites: Python 3.x (Standard library keyword module).
- Setup: None.
- How to Run: python question_01.py
- Expected Behavior: Prompts user for a variable name or executes built-in demonstration test cases.

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SOURCE CODE FILES:
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1. question_01.py
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import keyword

name = input("Enter the variable name to check: ")

if keyword.iskeyword(name):
    print(f"Invalid: '{name}' is a Python reserved keyword.")

elif not name.isidentifier():
    print("Invalid: Variable names can only contain letters (a–z, A–Z), \n"
          "         digits (0–9), and underscores (_), and cannot start with a number.")

else:
    print(f"Success: '{name}' is a valid variable name.")
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