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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 tree_build(self):
 """Build a tree from the taxonomy data present in this `ClassificationsDataFrame` or `SampleCollection`. Returns ------- `skbio.tree.TreeNode`, the root node of a tree that contains all the taxa in the current analysis and their parents leading back to the root node. """

        from skbio.tree import TreeNode

        # build all the nodes
        nodes = {}

        for tax_id in self.taxonomy.index:
            node = TreeNode(name=tax_id, length=1)
            node.tax_name = self.taxonomy["name"][tax_id]
            node.rank = self.taxonomy["rank"][tax_id]
            node.parent_tax_id = self.taxonomy["parent_tax_id"][tax_id]

            nodes[tax_id] = node

        # generate all the links
        for tax_id in self.taxonomy.index:
            try:
                parent = nodes[nodes[tax_id].parent_tax_id]
            except KeyError:
                if tax_id != "1":
                    warnings.warn(
                        "tax_id={} has parent_tax_id={} which is not in tree"
                        "".format(tax_id, nodes[tax_id].parent_tax_id)
                    )

                continue

            parent.append(nodes[tax_id])

        return nodes["1"]