Python problem with XML, why doesn't the standard library want to work?

Question

Python

The code

import xml.etree.ElementTree as ET
tree = ET.parse('country_data.xml')
root = tree.getroot()

Mistake

Traceback (most recent call last):
  File "F:\xml.py", line 1, in <module>
    import xml.etree.ElementTree as ET
  File "F:\xml.py", line 1, in <module>
    import xml.etree.ElementTree as ET
ModuleNotFoundError: No module named 'xml.etree'; 'xml' is not a package

What is the problem, I can't figure it out.