text: def binarySearch(alist, item):
  	    first = 0
        last = len(alist)-1
  	    found = False
  	
  	    while first<=last and not found:
  	        midpoint = (first + last)//2
  	        if alist[midpoint] == item:
  	            found = True
  	        else:
  	            if item < alist[midpoint]:
  	                last = midpoint-1
  	            else:
  	                first = midpoint+1
  	
  	    return found
  