import d4rl No module named 'flow' and 'carla'

[GuochenZhou]

When I tried to import d4rl, it get the following result:
Warning: Flow failed to import. Set the environment variable D4RL_SUPPRESS_IMPORT_ERROR=1 to suppress this message.
No module named 'flow'

Warning: CARLA failed to import. Set the environment variable D4RL_SUPPRESS_IMPORT_ERROR=1 to suppress this message.
No module named 'carla

[98729]

just ignore them

[Benjamin-So]

What is the error saying specifically? How come we can ignore it? Thanks in advance.