public function getSignedMessageStream(Message $message)
    {
        $child = $message->getChild(0);
        if ($child !== null) {
            return $child->getStream();
        }
        return null;
    }
public function getSignedMessageStream(Message $message)
    {
        $child = $message->getChild(0);
        if ($child !== null) {
            return $child->getStream();
        }
        return null;
    }
public function getSignedMessageStream ( Message $ message ) { $ child = $ message -> getChild ( 0 ) ; if ( $ child !== null ) { return $ child -> getStream ( ) ; } return null ; }
Returns a stream that can be used to read the content part of a signed
message, which can be used to sign an email or verify a signature.

The method simply returns the stream for the first child.  No
verification of whether the message is in fact a signed message is
performed.

Note that unlike getSignedMessageAsString, getSignedMessageStream doesn't
replace new lines.

@param Message $message
@return \Psr\Http\Message\StreamInterface or null if the message doesn't
have any children
Returns a stream that can be used to read the content part of a signed message which can be used to sign an email or verify a signature .