SPINEL_PROP_STREAM_DEBUG value

Debug Stream Format: `U` (stream, read only) This property is a streaming property, meaning that you cannot explicitly fetch the value of this property. The stream provides human-readable debugging output which may be displayed in the host logs. The location of newline characters is not assumed by the host: it is the NCP's responsibility to insert newline characters where needed, just like with any other text stream. To receive the debugging stream, you wait for `CMD_PROP_VALUE_IS` commands for this property from the NCP.