Convert scipy tree format to newick format (e.g. for working with figtree)

newick.py

from scipy.cluster import hierarchy

def tree2newick(node, newick, parentdist, leaf_names):
    if node.is_leaf():
        return f"{leaf_names[node.id]}:{parentdist - node.dist:.2f}{newick}"
    else:
        if len(newick) > 0:
            newick = f"):{parentdist - node.dist:.2f}{newick}"
        else:
            newick = ");"
        newick = tree2newick(node.get_left(), newick, node.dist, leaf_names)
        newick = tree2newick(node.get_right(), f",{newick}", node.dist, leaf_names)
        newick = f"({newick}"
        return newick

Z = linkage(dm, method="average")
tree = hierarchy.to_tree(Z, False)
newick = tree2newick(tree, "", tree.dist, leaf_names)