def dump_all(
    documents,
    stream=None,
    Dumper=Dumper,
    default_style=None,
    default_flow_style=None,
    canonical=None,
    indent=None,
    width=None,
    allow_unicode=None,
    line_break=None,
    encoding=enc,
    explicit_start=None,
    explicit_end=None,
    version=None,
    tags=None,
    block_seq_indent=None,
    top_level_colon_align=None,
    prefix_colon=None,
):
    # type: (Any, Optional[StreamType], Any, Any, Any, Optional[bool], Optional[int], Optional[int], Optional[bool], Any, Any, Optional[bool], Optional[bool], Any, Any, Any, Any, Any) -> Optional[str]   # NOQA
    """
    Serialize a sequence of Python objects into a YAML stream.
    If stream is None, return the produced string instead.
    """
    getvalue = None
    if top_level_colon_align is True:
        top_level_colon_align = max([len(str(x)) for x in documents[0]])
    if stream is None:
        if encoding is None:
            stream = StringIO()
        else:
            stream = BytesIO()
        getvalue = stream.getvalue
    dumper = Dumper(
        stream,
        default_style=default_style,
        default_flow_style=default_flow_style,
        canonical=canonical,
        indent=indent,
        width=width,
        allow_unicode=allow_unicode,
        line_break=line_break,
        encoding=encoding,
        explicit_start=explicit_start,
        explicit_end=explicit_end,
        version=version,
        tags=tags,
        block_seq_indent=block_seq_indent,
        top_level_colon_align=top_level_colon_align,
        prefix_colon=prefix_colon,
    )
    try:
        dumper._serializer.open()
        for data in documents:
            try:
                dumper._representer.represent(data)
            except AttributeError:
                # nprint(dir(dumper._representer))
                raise
        dumper._serializer.close()
    finally:
        try:
            dumper._emitter.dispose()
        except AttributeError:
            raise
            dumper.dispose()  # cyaml
    if getvalue is not None:
        return getvalue()
    return None

    Serialize a sequence of Python objects into a YAML stream.
    If stream is None, return the produced string instead.
    
dynaconf/vendor/ruamel/yaml/main.py