gistfile1.py

#!/usr/bin/env python
# encoding: utf-8
        
def er_search(l, t, i=0):
    mid = len(l) / 2 
    if l[mid] == t:                                                                                                                                     
        return mid + i
    elif len(l) == 1:
        return None
    return er_search(l[:mid], t, i=i) if l[mid] > t else er_search(l[mid: ], t, i=i+mid)