Close a child position - alias for rebalance(0, child). This will also
        flatten (close out all) the child's children.

        Args:
            * child (str): Child, specified by name.

def close(self, child):
        """
        Close a child position - alias for rebalance(0, child). This will also
        flatten (close out all) the child's children.

        Args:
            * child (str): Child, specified by name.
        """
        c = self.children[child]
        # flatten if children not None
        if c.children is not None and len(c.children) != 0:
            c.flatten()

        if c.value != 0. and not np.isnan(c.value):
            c.allocate(-c.value)