gistfile1.txt

from datetime import datetime

def is_leap_year(year):
    return (year % 400 == 0) or (year % 100 != 0 and year % 4 == 0)

def calculate_leap_age(birthdate, current_date):
    birthdate = datetime.strptime(birthdate, '%Y-%m-%d')
    current_date = datetime.strptime(current_date, '%Y-%m-%d')
    
    start_year = birthdate.year if birthdate.month > 2 else birthdate.year + 1
    end_year = current_date.year - 1 if current_date.month < 2 or (current_date.month == 2 and current_date.day < 29) else current_date.year

    return sum(is_leap_year(year) for year in range(start_year, end_year + 1))