fail merge sort

fail_merge.py

def merge(array1, array2):
    a_index = 0
    b_index = 0    
    result = []
    
    # wrong while condition 
    while a_index < len(array1) and b_index < len(array2):
        if array1[a_index] > array2[b_index]:
            result.append(array2[b_index])
            b_index+=1
        else:
            result.append(array1[a_index])
            a_index+=1

    return result
        
        
a = [1, 2, 5]
b = [3, 4, 6]
print(merge(a, b))

# [1, 2, 3, 4, 5]

What is wrong:

1. wrong while condition : in this condition, if one array index reach to end of array, while is stop in spite of remains of another array
2. check when one array ended in advance : remains of another array must be added to result