class Employee:
    def __init__(self, name, address, employee_number):
        self.name = name
        self.__address = address
        self.__emp_num = employee_number
    
    def get_address(self):
        return self.__address
    def set_address(self, address):
        #TODO in later version: validate address
        self.__address = address
    
    def get_number(self):
        return self.__emp_num
    
    def __eq__(self, other):
        return self.__emp_num == other.__emp_num
    
    def __str__(self):
        return self.name

class Company:
    def __init__(self, name, address, employee_count, employees):
        self.name = name
        self.__address = address
        
        self.__employee_count = employee_count
        self.__employees = employees
    
    def get_address(self):
        return self.__address
    def set_address(self, address):
        #TODO in later version: validate address
        self.__address = address
    
    def get_employee_count(self):
        return self.__employee_count
    def set_employee_count(self, count):
        if not isinstance(count, int):
            raise TypeError('Employee count must be a positive integer.')
        elif count < 0:
            raise ValueError('Employee count must be a positive integer.')
        
        self.__employee_count = count
        
    def add_employee(self, employee):
        if not isinstance(employee, Employee):
            raise TypeError('Wrong type')
        self.__employees.append(employee)
    def remove_employee(self, employee):
        self.__employees.remove(employee)
    def get_employees(self):
        return self.__employees
    
    def split(self, new_company_name):
        '''
            This method is used when a company is split into two companies.
            
            new_company_name represents the name of the new company (the one
            returned by this method.  All other changes to the companies
            will need to be done after the split, using the appropriate
            methods.
        '''
        return Company(new_company_name, self.__address, self.__employee_count, self.__employees)
    
    def merge(self, other_company):
        '''
            This method merges two companies and modifies this company to
            reflect those changes.  This company keeps its name and
            address, so if those need to be changed, use the appropriate
            methods.
        '''
        self.__employee_count += other_company.__employee_count
        self.__employees += other_company.__employees