Apply a Custom Function

Categorize employees into salary bands using a custom function.

Available Data:

DataFrame df with columns: name, department, salary, age, city

Requirements:

• Add a salary_band column based on salary:
• - Below 70000: 'Junior'
• - 70000-99999: 'Mid'
• - 100000+: 'Senior'
• Use apply() with a function or lambda