def dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True,
        allow_nan=True, cls=None, indent=None, separators=None,
        encoding='utf-8', default=None, sort_keys=False, **kw):
    """Serialize ``obj`` as a DSON formatted stream to ``fp`` (a
    ``.write()``-supporting file-like object).

    If ``skipkeys`` is true then ``dict`` keys that are not basic types
    (``str``, ``unicode``, ``int``, ``long``, ``float``, ``bool``, ``None``)
    will be skipped instead of raising a ``TypeError``.

    If ``ensure_ascii`` is true (the default), all non-ASCII characters in the
    output are escaped with ``\\uXXXX`` sequences, and the result is a ``str``
    instance consisting of ASCII characters only.  If ``ensure_ascii`` is
    ``False``, some chunks written to ``fp`` may be ``unicode`` instances.
    This usually happens because the input contains unicode strings or the
    ``encoding`` parameter is used. Unless ``fp.write()`` explicitly
    understands ``unicode`` (as in ``codecs.getwriter``) this is likely to
    cause an error.

    If ``check_circular`` is false, then the circular reference check
    for container types will be skipped and a circular reference will
    result in an ``OverflowError`` (or worse).

    If ``allow_nan`` is false, then it will be a ``ValueError`` to
    serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``)
    in strict compliance of the DSON specification, instead of using the
    JavaScript equivalents (``NaN``, ``Infinity``, ``-Infinity``).

    If ``indent`` is a non-negative integer, then DSON array elements and
    object members will be pretty-printed with that indent level. An indent
    level of 0 will only insert newlines. ``None`` is the most compact
    representation.  Since the default item separator is ``', '``,  the
    output might include trailing whitespace when ``indent`` is specified.
    You can use ``separators=(',', ': ')`` to avoid this.

    If ``separators`` is an ``(item_separator, dict_separator)`` tuple
    then it will be used instead of the default ``('and ', 'is ')`` separators.
    ``('and', 'is')`` is the most compact DSON representation.

    ``encoding`` is the character encoding for str instances, default is UTF-8.

    ``default(obj)`` is a function that should return a serializable version
    of obj or raise TypeError. The default simply raises TypeError.

    If *sort_keys* is ``True`` (default: ``False``), then the output of
    dictionaries will be sorted by key.

    To use a custom ``DSONEncoder`` subclass (e.g. one that overrides the
    ``.default()`` method to serialize additional types), specify it with
    the ``cls`` kwarg; otherwise ``DSONEncoder`` is used.

    """
    # cached encoder
    if (not skipkeys and ensure_ascii and
        check_circular and allow_nan and
        cls is None and indent is None and separators is None and
        encoding == 'utf-8' and default is None and not sort_keys and not kw):
        iterable = _default_encoder.iterencode(obj)
    else:
        if cls is None:
            cls = DSONEncoder
        iterable = cls(skipkeys=skipkeys, ensure_ascii=ensure_ascii,
            check_circular=check_circular, allow_nan=allow_nan, indent=indent,
            separators=separators, encoding=encoding,
            default=default, sort_keys=sort_keys, **kw).iterencode(obj)
    # could accelerate with writelines in some versions of Python, at
    # a debuggability cost
    for chunk in iterable:
        fp.write(chunk)