def isbool(s):
    """
    Checks whether the string ``s`` represents a boolean.
    
    The string requires Python capitalization (e.g. 'True', not 'true').
    
    :param s: the candidate string to test
    :type s:  ``str``
    
    :return: True if s is the string representation of a boolean
    :rtype:  ``bool``
    """
    if type(s) in [int,float,bool]:
        return True
    elif (type(s) != str):
        return False
    return s in ['True','False']