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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def _textlist(self, _addtail=False):
    '''Returns a list of text strings contained within an element and its sub-elements.

    Helpful for extracting text from prose-oriented XML (such as XHTML or DocBook).
    '''
    result = []
    if (not _addtail) and (self.text is not None):
        result.append(self.text)
    for elem in self:
        result.extend(elem.textlist(True))
    if _addtail and self.tail is not None:
        result.append(self.tail)
    return result