binarySearch.py

def binary_search(sequence,item):
    start_index = 0
    end_index = len(sequence) - 1 # finds the last index 
    
    
    while start_index <= end_index:
        mid_point = start_index  + (end_index - start_index)//2  #Finds the mid index of the sequence using the start and end index
        mid_point_value = sequence[mid_point]
        if mid_point == item: 
            return mid_point # if item is the mid point the function will end
        elif item < mid_point_value:
            end_index = mid_point - 1  # if the item is smaller than the mid point a new end index will be set which is the index one before the middle point and the loop continues
        else: 
            start_index = mid_point + 1 # if the item is bigger than the mid point the starting index will be set to the right index of the middle point and then the loop continues
    return None

sequence = [1,2,3,4,5,6,7,8,9]
print(binary_search(sequence, 7))