human
Here's a good function header given the following:
I wrote the below code

    def _extract(node):
        if isinstance(node, nodes.Expr):
            return node.value
        return node
    requested_lines = []
    for (idx, line) in enumerate(code.splitlines()):
        if line.strip().endswith(_STATEMENT_SELECTOR):
            requested_lines.append((idx + 1))
    tree = parse(code, module_name=module_name)
    extracted = []
    if requested_lines:
        for line in requested_lines:
            extracted.append(_find_statement_by_line(tree, line))
    extracted.extend(_extract_expressions(tree))
    if (not extracted):
        extracted.append(tree.body[(-1)])
    extracted = [_extract(node) for node in extracted]
    if (len(extracted) == 1):
        return extracted[0]
    return extracted

What's a good function header?
assistant
#Here's a good function header.

def extract_node(code, module_name=''):