import test_import
...
mods = HotImport([test_import]) # Update all the 'test_import' module

from test_import import say_hello
... #                                                                                        
mods = HotImport([say_hello]) # Update only the 'test_import.say_hello' function and the 'say_hello' function

from test_import import TestClass as TC
...
mods = HotImport([TC]) # Update all the 'TestClass' class and 'TC'

t = TC()