binary.py

def isIn(char, aStr):
    '''
    char: a single character
    aStr: an alphabetized string

    returns: True if char is in aStr; False otherwise
    '''
    # Your code here

    if not aStr or len(aStr) == 1 and aStr[0] is not char:
        return False

    else:
        if aStr[int(len(aStr)/2)] == char:
            return True
            #
        elif aStr[int(len(aStr)/2)] < char:
            return isIn(char, aStr[int(len(aStr)/2):])
            #
        elif aStr[int(len(aStr)/2)] > char:
            return isIn(char, aStr[:int(len(aStr)/2)])
            #


print(isIn('d', 'd'))


## isIn('d', 'abcdefghijklmnopqrstuvwxyz')