decode incoming quoted-printable content, stripping
out soft line breaks and translating =XY sequences
into their decoded byte/octet. The output encoding/representation
is still a String, not a sequence of bytes.
encode converts a sequence of characeter _octets_ into
quoted-printable form; suitable for transmission in MIME
payloads. Note the stress on _octets_; it is assumed that
you have already converted Unicode into a <=8-bit encoding
(UTF-8, most likely.)