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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 children(self):
 r"""Immediate children of this TeX element that are valid TeX objects. This is equivalent to contents, excluding text elements and keeping only Tex expressions. :return: generator of all children :rtype: Iterator[TexExpr] \item Hello <BLANKLINE> """

        for child in self.expr.children:
            node = TexNode(child)
            node.parent = self
            yield node