You are provided with a CSV file named employeeInfo.csv containing data about employees. Your task is to write a Python program to analyze this data. You cannot use libraries like pandas; only built$-$in Python functions and data structures can be used.

Create a function named find$\_$longest$\_$serving$\_$employees that identifies the employee$($s$)$ with the longest tenure $($in years$)$ in the company. The function should return a list of tuples, each tuple containing the first name, last name, and the tenure in years of an employee. Consider the DateOfJoining field for calculating the tenure. The month and day of joining are irrelevant i$.$e$.,$ a person who joined in Jan $2023$ and a person who joined in Dec $2023,$ both will have one year of service.

CSV file Example:

SNo FirstName LastName DepartmentName DateOfJoining

$1$ Will Bradshaw Biology $6/4/2016$

$2$ Bentley Alvarado Mathematics $9/15/2020$

$3$ Jayleen Burns ComputerScience $8/18/2006$

$4$ Aaliyah Barber SocialScience $6/4/2000$

$5$ Dixie Hester Biology $7/28/2011$

$6$ Oswaldo Brooks English $3/27/2012$