"""
    Rename this file from list_op_shell.py to list_op.py and write the function bodies below.
"""
def average(num_list):
    """
    Returns the average of numbers in a list.
    Returns 0 for an empty list.
    Replace "pass" with your code below and remove this comment line.
    """
    
# 
#   
list_1 = [1,3,5,9,8,7,1,1]
#
# code for the average of list_1
#
#  step by step algorithm
#  average = sum of the list / number of elements in the list.
#  list_1 average: 35 / 8 = 4.375
#
#  sum of the list.

num_sum = sum(list_1)
print(num_sum)

#  number of elements in the list.
print(list_1.count(1))
print(list_1.count(4))
print(list_1.count(7))

print(len(list_1))
list_2 = []
print(sum(list_2))
print(len(list_2))

def average(num_list):
    """
    Returns the average of numbers in a list.
    Returns 0 for an empty list.
    Replace "pass" with your code below and remove this comment line.
    """
    num_sum = sum(num_list)
    num_count = len(num_list)
    if num_count == 0:  # one way to handle division by Zero
        return None  # missing information.
    else:
        return num_sum / num_count
        
    
def average2(num_list):
    """
    Returns the average of numbers in a list.
    Returns 0 for an empty list.
    Replace "pass" with your code below and remove this comment line.
    """
    return sum(num_list) / len(num_list)
    
print(f"average(list_1): {average(list_1)}")
print(f"average2(list_1): {average2(list_1)}")

print(f"average(list_2): {average(list_2)}")
#   print(f"average2(list_2): {average2(list_2)}")

def count_greater_occurrences(num_list, threshold):
    """
    Counts the occurrences of elements in a list that is greater than a specific threshold.
    Replace "pass" with your code below and remove this comment line.
    """
    
list_a = [1,5,3,7,6,4,7,5]
threshold_a = 4
#   result: 5

#   algorithm:
#       count <- 0
#       loop through element e in list_a:
#           if e > threshold_a
#                count <- count + 1
#       return count

count = 0
for item in list_a:
    if item > threshold_a:
        count += 1
print(f"count of elements in list_a that is greater than 4: {count}")

list_b = [1,1,2,3,-9,0]
threshold_b =4
count = 0
for item in list_b:
    if item > threshold_b:
        count += 1
print(f"count of elements in list_b that is greater than 4: {count}")