Unexpected behavior of binary search algorithm in python -

i new python. while trying make binary search function , facing , unexpected problem. don't understand why happening. tried modify code, result same every time. here code:

def bsearch(s,e,first,last,calls):     print(first,last,calls)     if((first-last)<2):         return (s[first]==e or s[last]==e)     mid = first + int((last-first)/2)     if (s[mid]==e):         return true     if (s[mid]>e):         return bsearch(s,e,first,mid-1,calls+1)     else:         return bsearch(s,e,mid+1,last,calls+1)  def search(s,e):     bsearch(s,e,0,len(s)-1,1) 

this type in shell , output:

>>> s=[1,2,3,4,5,6,7,8,9,10,11,12,13,15,16] >>> search(s,5) 

output:

0 14 1 

thats it. doesn't search element in list.

the mistake right here:

if((first-last)<2): #this less 2 

should be:

if((last-first)<2):