def _break(bitstring,groupsize):
    """
    Break a binary string into groups of groupsize digits.
    For example, _break('1100001111',4) returns '11 0000 1111'
    :param bitstring: The ASCII binary string to break into groups
    :param groupsize: The number of bits to group together in each group
    :return: A string with spaces inserted between each group.
    """
    broken = ''
    for i in range(len(bitstring)-groupsize,-1,-groupsize):
        broken = bitstring[i:i+groupsize] + ' ' + broken
    if len(bitstring)%groupsize > 0: # Avoid adding space before empty left-most group
        broken = bitstring[0:len(bitstring)%groupsize] + ' ' + broken
    return broken[:-1]