session - session instance as returned by libssh2_session_init_ex(3)blocking - Set to a non-zero value to make the channel block, or zero to make it non-blocking.
Set or clear blocking mode on the selected on the session. This will instantly affect any channels
associated with this session. If a read is performed on a session with no data currently available, a
blocking session will wait for data to arrive and return what it receives. A non-blocking session will
return immediately with an empty buffer. If a write is performed on a session with no room for more data,
a blocking session will wait for room. A non-blocking session will return immediately without writing
anything.