ast.unparse

Python 3.9 introduces a new function ast.unparse. It accepts a parsed AST and produces a Python code. This code if parsed will produce the same AST:

import ast
tree = ast.parse('a=(1+2)+3 # example')
ast.unparse(tree)
# '\na = 1 + 2 + 3'

It knows nothing about the initial formatting and comments. So, it's not a code formatter but a tool to simplify visual AST analysis. Also, it can be used for code generation.