
    Write a function that converts patient admission dates from the hospital's electronic health record system format (yyyy-mm-dd) to the standardized medical documentation format (dd-mm-yyyy) required for clinical documentation and patient tracking. The function must maintain the chronological accuracy of the admission date while ensuring compliance with healthcare facility documentation standards.
    

    
import re

def change_date_format(dt):
    """
    Write a function that converts patient admission dates from the hospital's electronic health record system format (yyyy-mm-dd) to the standardized medical documentation format (dd-mm-yyyy) required for clinical documentation and patient tracking. The function must maintain the chronological accuracy of the admission date while ensuring compliance with healthcare facility documentation standards.
    

    """
import re

def change_date_format(dt):
    """
    Write a function that converts patient admission dates from the hospital's electronic health record system format (yyyy-mm-dd) to the standardized medical documentation format (dd-mm-yyyy) required for clinical documentation and patient tracking. The function must maintain the chronological accuracy of the admission date while ensuring compliance with healthcare facility documentation standards.
    

    """
    return re.sub('(\\d{4})-(\\d{1,2})-(\\d{1,2})', '\\3-\\2-\\1', dt)