Python - Move and replace if same file name already exists

#!/usr/bin/python3
 
# Create test-dir/ directory.
import pathlib
dirname = "test-dir"
pathlib.Path(dirname).mkdir(exist_ok=True)
 
# Create a original file.
import os
filename = "test-file.txt"
filepath = os.path.join(dirname, filename)
fstream = open(filepath, "w")
fstream.write("original")
fstream.close()
 
# Create a file.
fstream = open(filename, "a")
fstream.write("hello")
fstream.close()
 
# Move file and overwrite it if it exists.
import os
import shutil
def move_file(filepath, dest):
    # Convert to absolute paths.
    filepath = os.path.abspath(filepath)
    dest     = os.path.abspath(dest)
 
    # If destination is a directory, use full path, including filename.
    if os.path.isdir(dest):
        filename = os.path.basename(filepath)
        dest_filepath = os.path.join(dest, filename)
        shutil.move(filepath, dest_filepath)
    else:
        shutil.move(filepath, dest)
 
 
move_file(filename, dirname)
# move_file(filename, os.path.join(dirname, filename))