def binarysearch(a,n,index):
  mid=int(len(a)/2)
  if(n==a[mid]):
    return (mid+index+1)
  elif(n>a[mid]):
    index=index+mid
    return binarysearch(a[(mid+1):],n,index)
  elif(n<a[mid]):
    return binarysearch(a[0:mid],n,index)

This worked well