def METHOD_NAME(
    name: str,
    args: List[str],
    body: List[str],
    *,
    return_type: Any = MISSING,
    indentlevel: int = 0,
    indentspaces: int = 4,
    argsep: str = ", ",
) -> str:
    """Generate function source code from args and body."""
    indent = " " * indentspaces
    curindent = indent * indentlevel
    nextindent = indent * (indentlevel + 1)
    return_annotation = ""
    if return_type is not MISSING:
        return_annotation = "->_return_type"
    bodys = "\n".join(f"{nextindent}{b}" for b in body)
    return (
        f"{curindent}def {name}({argsep.join(args)}){return_annotation}:\n" f"{bodys}"
    )