'Return a new L{TextBlock}. The block has not been appended to this
book.
@param textStyle: If None the default text style is used
@type textStyle: L{TextStyle}
@param blockStyle: If None the default block style is used.
@type blockStyle: L{BlockStyle}'

def create_text_block(self, textStyle=None, blockStyle=None, **settings):

    if (not textStyle):
        textStyle = self.defaultTextStyle
    if (not blockStyle):
        blockStyle = self.defaultBlockStyle
    return TextBlock(textStyle=textStyle, blockStyle=blockStyle, **settings)
