Encode the:term:`bytes-like object` *s* using Base64 and return the encoded

:class:`bytes`.

Optional *altchars* must be a:term:`bytes-like object` of at least

length 2 (additional characters are ignored) which specifies an alternative

alphabet for the ``+`` and ``/`` characters. This allows an application to e.g.

generate URL or filesystem safe Base64 strings. The default is ``None``, for

which the standard Base64 alphabet is used.

Optional *altchars* must be a:term:`bytes-like object` of length 2 which

specifies an alternative alphabet for the ``+`` and ``/`` characters.

This allows an application to e.g. generate URL or filesystem safe Base64

strings. The default is ``None``, for which the standard Base64 alphabet is used.

May assert or raise a a:exc:`ValueError` if the length of *altchars* is not 2. Raises a

:exc:`TypeError` if *altchars* is not a:term:`bytes-like object`.

..function::b64decode(s, altchars=None, validate=False)

Decode the Base64 encoded:term:`bytes-like object` or ASCII string

*s* and return the decoded:class:`bytes`.

Optional *altchars* must be a:term:`bytes-like object` or ASCII string of

at leastlength 2(additional characters are ignored) which specifies the

alternative alphabet used instead of the``+`` and ``/`` characters.

Optional *altchars* must be a:term:`bytes-like object` or ASCII string

oflength 2which specifies the alternative alphabet used instead of the

``+`` and ``/`` characters.

A:exc:`binascii.Error` exception is raised

if *s* is incorrectly padded.

For more information about the strict base64 check, see:func:`binascii.a2b_base64`

May assert or raise a:exc:`ValueError` if the length of *altchars* is not 2.

..function::standard_b64encode(s)