Smart contract general structure

GeneralStructure.sol

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.13;

contract GeneralStructure{
    // state variables
    uint public stateUintVariable;
    string stateStringVariable;
    address owner;
    Person person;

    // enumeration
    enum Gender{male, female}

    // struct
    struct Person{
        string name;
        uint age;
        Gender gender;
        bool isEmployed;
        uint[] bankAccountNumbers;
    }
    
    // mapping
    mapping(address => Person) people;
    
    // constructor
    constructor(uint _stateUintVariable, string memory _stateStringVariable){
        owner = msg.sender;
        stateUintVariable = _stateUintVariable;
        stateStringVariable = _stateStringVariable;
    }

    // modifier
    modifier onlyBy(){
        require(msg.sender == owner, "Only owner");
        _;
    }

    // event
    event ageRead(address, uint);

    // function
    function addPerson(address _addressIdentifier, string memory _name, uint _age, bool _isEmployed) public {
        Person memory newHuman = Person(_name, _age, Gender.male, _isEmployed, new uint[](3));
        people[_addressIdentifier] = newHuman;
    }

     // function
    function getAge(address _addressIdentifier) onlyBy()  external returns (uint age){
        person = people[_addressIdentifier];
        emit ageRead(_addressIdentifier, person.age);
        return person.age;
    }
}