The pre-requisite of the binary search algorithm is sorted data. The algorithm iteratively divides a list into two parts and keeps a track of the lowest and highest indices until it finds the value it is looking for:

def BinarySearch(list, item): 
   first = 0 
   last = len(list)-1 
   found = False 

while first<=last and not found:         
    midpoint = (first + last)//2         
    if list[midpoint] == item:             
        found = True         
    else:             
        if item < list[midpoint]:                 
            last = midpoint-1             
        else:                 
            first = midpoint+1     
return found

The output is as follows:

Note that calling the BinarySearch function will return True if the value is found in the input list.