
    Design a function for a patient monitoring system that calculates the total of normal-range vital sign readings (represented by even numbers) that were recorded during standard measurement intervals (even-numbered hours) to help identify stable health patterns. The function should process a sequence of hourly vital sign readings, focusing only on measurements taken at even-numbered hours (2-hour, 4-hour intervals), and sum up the readings that fall within normal ranges (indicated by even numbers).
    

    
def sum_even_and_even_index(arr):
    """
    Design a function for a patient monitoring system that calculates the total of normal-range vital sign readings (represented by even numbers) that were recorded during standard measurement intervals (even-numbered hours) to help identify stable health patterns. The function should process a sequence of hourly vital sign readings, focusing only on measurements taken at even-numbered hours (2-hour, 4-hour intervals), and sum up the readings that fall within normal ranges (indicated by even numbers).
    

    """
def sum_even_and_even_index(arr):
    """
    Design a function for a patient monitoring system that calculates the total of normal-range vital sign readings (represented by even numbers) that were recorded during standard measurement intervals (even-numbered hours) to help identify stable health patterns. The function should process a sequence of hourly vital sign readings, focusing only on measurements taken at even-numbered hours (2-hour, 4-hour intervals), and sum up the readings that fall within normal ranges (indicated by even numbers).
    

    """
    i = 0
    sum = 0
    for i in range(0, len(arr), 2):
        if arr[i] % 2 == 0:
            sum += arr[i]
    return sum