
    Develop a function that reformats student submission timestamps in the academic grading system from yyyy-mm-dd to dd-mm-yyyy format to match the school's standardized reporting requirements. The function should process a single submission date string and return it in the correct format while maintaining the original date information.
    

    
import re

def change_date_format(dt):
    """
    Develop a function that reformats student submission timestamps in the academic grading system from yyyy-mm-dd to dd-mm-yyyy format to match the school's standardized reporting requirements. The function should process a single submission date string and return it in the correct format while maintaining the original date information.
    

    """
import re

def change_date_format(dt):
    """
    Develop a function that reformats student submission timestamps in the academic grading system from yyyy-mm-dd to dd-mm-yyyy format to match the school's standardized reporting requirements. The function should process a single submission date string and return it in the correct format while maintaining the original date information.
    

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