def invoke_shell(self, term='<STR_LIT>', width=<NUM_LIT>, height=<NUM_LIT>):
chan = self._transport.open_session()<EOL>chan.get_pty(term, width, height)<EOL>chan.invoke_shell()<EOL>return chan<EOL>
Start an interactive shell session on the SSH server.  A new L{Channel}
is opened and connected to a pseudo-terminal using the requested
terminal type and size.

@param term: the terminal type to emulate (for example, C{"vt100"})
@type term: str
@param width: the width (in characters) of the terminal window
@type width: int
@param height: the height (in characters) of the terminal window
@type height: int
@return: a new channel connected to the remote shell
@rtype: L{Channel}

@raise SSHException: if the server fails to invoke a shell