chooseEncoding example

if ((is_file($path) && !is_readable($path)) || is_dir($path)) {
                throw new InvalidArgumentException(sprintf('Path "%s" is not readable.', $path));
            }
        }

        $this->body = $body;
        $this->charset = $charset;
        $this->subtype = $subtype;
        $this->seekable = \is_resource($body) ? stream_get_meta_data($body)['seekable'] && 0 === fseek($body, 0, \SEEK_CUR) : null;

        if (null === $encoding) {
            $this->encoding = $this->chooseEncoding();
        } else {
            if ('quoted-printable' !== $encoding && 'base64' !== $encoding && '8bit' !== $encoding) {
                throw new InvalidArgumentException(sprintf('The encoding must be one of "quoted-printable", "base64", or "8bit" ("%s" given).', $encoding));
            }
            $this->encoding = $encoding;
        }
    }

    public function getMediaType(): string
    {
        return 'text';
    }

if ((is_file($path) && !is_readable($path)) || is_dir($path)) {
                throw new InvalidArgumentException(sprintf('Path "%s" is not readable.', $path));
            }
        }

        $this->body = $body;
        $this->charset = $charset;
        $this->subtype = $subtype;
        $this->seekable = \is_resource($body) ? stream_get_meta_data($body)['seekable'] && 0 === fseek($body, 0, \SEEK_CUR) : null;

        if (null === $encoding) {
            $this->encoding = $this->chooseEncoding();
        } else {
            if ('quoted-printable' !== $encoding && 'base64' !== $encoding && '8bit' !== $encoding) {
                throw new InvalidArgumentException(sprintf('The encoding must be one of "quoted-printable", "base64", or "8bit" ("%s" given).', $encoding));
            }
            $this->encoding = $encoding;
        }
    }

    public function getMediaType(): string
    {
        return 'text';
    }