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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_unique_child_value(xtag, eltname):
 """Get the text content of the unique child element under xtag with name eltname"""

    xelt = _get_unique_child(xtag, eltname)
    if xelt is None:
        return None
    else:
        return xelt.text