Создать файл xml schema на основе корректного xml

# -*- coding: utf-8 -*-
# using python 2.7.3
""" Program using classes TestResult and Student to load data
from a file to a collection. At the end script output to the console
collection lines in the following format: login;test;date;mark """
 
from datetime import date as datetype
try:
    from lxml import etree
except ImportError:
    import xml.etree.ElementTree as etree
 
class TestResult:
    ''' Class describes tests.
        TestResult(name str, date str, mark str) ->
        instance(nameTest str, dateTest datetype(YYYY,MM,DD), markTest int)
    '''
    def __init__(self, name='', date='', mark=''):
        self.nameTest = name
        self.dateTest = datetype(*map(int,date.split('-')))
        self.markTest = int(float(mark)*10) 
 
    def __str__(self):
        return '{0};{1};{2}'.format(self.nameTest, self.dateTest, 
            self.markTest/10.)
 
class Student():
    """Class for Students
        Student(login str, list_tests list) -> instance(str, list)
    """
    def __init__(self, login='',list_tests=[]):
        self.loginStudent = login
        self.listTestStudent = list_tests
 
    def __str__(self):
        return '\n'.join(('%s;%s;%s;%s' % (self.login, 
            el.nameTest, el.dateTest, el.markTest/10.) \
        for el in self.listTestStudent))
 
 
def main():
    with open('results.xml') as f:
        xml_file_tree = etree.parse(f)
        root = xml_file_tree.getroot()
        list_students = list()
        for child in root:
            if child.tag == 'student':
                student_temp = Student()
                for subchild in child:
                    if subchild.tag == "login":
                        student_temp.login = subchild.text
                    if subchild.tag == 'tests':
                        for test in subchild:
                            test_temp = TestResult(test.attrib['name'], 
                                test.attrib['date'], test.attrib['mark'])
                            student_temp.listTestStudent.append(test_temp) 
                print student_temp
                list_students.append(student_temp)
 
if __name__ == '__main__':
    main()