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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 get_edu_text(text_subtree):
 """return the text of the given EDU subtree, with '_!'-delimiters removed."""

    assert text_subtree.label() == 'text', "text_subtree: {}".format(text_subtree)
    edu_str = u' '.join(word for word in text_subtree.leaves())
    return re.sub('_!(.*?)_!', '\g<1>', edu_str)