def __init__(self, c_path, expected_blob, message=None):
        """:param c_path: the problematic path
        :param expected_blob: if True, a blob was expected but a folder was found.
                              if False, a folder was expected but a blob was found
        :param message: optional message"""
        if not message:
            message = 'Invalid file type at %r (expected %s)' % \
                      (c_path, 'blob' if expected_blob else 'folder')
        super(CInvalidFileTypeError, self).__init__(message)
        self.path = c_path
        self.expected_blob = expected_blob