How to use the paramiko.SFTPClient function in paramiko

import paramiko
        except ImportError:
            print "SFTP: You will need to install the paramiko library to have sftp support."
            raise
        url = urlfunctions.url_split(url)
        if not url.port:
            url.port = 22
        self._transport = paramiko.Transport((url.hostname, url.port))
        if not url.username:
            url.username = getpass.getuser()
        if not url.password:
            url.password = getpass.getpass(
                "SFTP: Please enter the password for %s@%s:" % (url.username, url.hostname)
                )
        self._transport.connect(username=url.username, password=url.password)
        self._connection = paramiko.SFTPClient.from_transport(self._transport)

def get_results(is_all):
    """ Get results from server.
    """
    # Starting with clean slate
    cleanup()

    # Read private keys
    key = paramiko.RSAKey.from_private_key_file(KEY_DIR)

    # Open a transport
    transport = paramiko.Transport(('acropolis.uchicago.edu', 22))
    transport.connect(username='eisenhauer', pkey=key)

    # Initialize SFTP connection
    sftp = paramiko.SFTPClient.from_transport(transport)

    # Get files
    sftp.chdir(CLIENT_DIR)

    # Get candidate directories that contain results on the server.
    results = []
    for candidate in sftp.listdir('.'):
        # Determine status of directory or file
        if isdir(candidate, sftp):
            if 'module' in candidate:
                continue
            results += [candidate]

    # Get all material from the results directories.
    for result in results:
        os.mkdir(result), os.chdir(result), sftp.chdir(result)

def get_ftp_connection(self):
        transport = paramiko.Transport(self.host)
        transport.connect(username=self.username, password=self.password)
        sftp = paramiko.SFTPClient.from_transport(transport)
        return sftp

# Create a sql dump
    client = paramiko.SSHClient()
    client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    client.connect(hostname, username=username, password=password)
    stdin, stdout, stderr = client.exec_command('scl enable postgresql92 "./dump_sidewalk_tables.sh %s"' % sql_dump_filename)
    stdout.read()
    client.close()
    print "Created the database dump %s on the remote server" % sql_dump_filename

    # Download the file
    print "Opening a sftp port"
    port = 22
    transport = paramiko.Transport((hostname, port))
    transport.connect(username=username, password=password)
    sftp = paramiko.SFTPClient.from_transport(transport)
    print "Downloading the database dump %s to local path %s" % (remote_filename, sql_dump_filename)
    sftp.get(remote_filename, sql_dump_filename)
    sftp.close()
    transport.close()
    print "Download complete"

def sftp_upload_file(host,user,password,ssh_port,server_path, local_path):
    try:
        t = paramiko.Transport((host, ssh_port))
        t.connect(username=user, password=password)
        sftp = paramiko.SFTPClient.from_transport(t)
        sftp.put(local_path, server_path)
        t.close()
    except Exception, e:
        print e

def _make_sftp(self):
        transport = self.client.get_transport()
        transport.open_session()
        return paramiko.SFTPClient.from_transport(transport)

def sftp_ctx():
    """
    Context manager that provides an SFTP client object
    (an SFTP session across an open SSH Transport)
    """
    transport = paramiko.Transport((current_app.config['SFTP_HOSTNAME'],
                                    int(current_app.config['SFTP_PORT'])))
    transport.connect(username=current_app.config['SFTP_USERNAME'],
                      pkey=paramiko.RSAKey(filename=current_app.config['SFTP_RSA_KEY_FILE']))
    sftp = paramiko.SFTPClient.from_transport(transport)
    try:
        yield sftp
    except Exception as e:
        raise paramiko.SFTPError("Exception occurred with SFTP: {}".format(e))
    finally:
        sftp.close()
        transport.close()

def make_sftp(self):
        """Make SFTP client from open transport"""
        transport = self.client.get_transport()
        transport.open_session()
        return paramiko.SFTPClient.from_transport(transport)

def get_results(is_all):
    """ Get results from server.
    """
    # Starting with clean slate
    cleanup()

    # Read private keys
    key = paramiko.RSAKey.from_private_key_file(KEY_DIR)

    # Open a transport
    transport = paramiko.Transport(('acropolis.uchicago.edu', 22))
    transport.connect(username='eisenhauer', pkey=key)

    # Initialize SFTP connection
    sftp = paramiko.SFTPClient.from_transport(transport)

    # Get files
    sftp.chdir(CLIENT_DIR)

    # Get results directory, this is always downloaded.
    get_directory('rslts', sftp)

    # If requested, also download all intermediate results as well.
    if is_all:
        for candidate in sftp.listdir('.'):
            # Only directories are even potentially interesting.
            if not isdir(candidate, sftp):
                continue
            # Check if directory name can be transformed into a float.
            try:
                float(candidate)

host_server = self.fqdn_to_shortname(app.host_server)

    self.logger.info("Bootstrapping {hostname} on server: {host_server} port: {port}".format(
      hostname=app.hostname, 
      host_server=host_server,
      port=app.ssh_port))

    try:
      ssh = paramiko.SSHClient()
      ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
      ssh.connect(hostname=host_server, port=app.ssh_port, 
        username='root', password='newroot')

      transport = paramiko.Transport((host_server, app.ssh_port))
      transport.connect(username = 'root', password = 'newroot')
      sftp = paramiko.SFTPClient.from_transport(transport)
      sftp.put('bootstrap.sh', '/root/bootstrap.sh')
      sftp.put('start.sh', '/root/start.sh')

      ssh.exec_command("chmod +x /root/bootstrap.sh")
      ssh.exec_command("chmod +x /root/start.sh")
      stdin, stdout, stderr = ssh.exec_command("bash /root/start.sh")
      self.logger.debug(''.join(stdout.readlines()))
      ssh.close()
    except SSHException:
      self.logger.error("Failed to log into server.  Shutting it down and cleaning up the mess.")
      self.delete_container(app.host_server, app.container_id)