Hi Team, please can you answer the below questions from my client. 
I have a couple of questions on the recommended Python package and required credentials please.
 
There are three Python packages available:
 
https://pypi.org/project/refinitiv-data/
https://pypi.org/project/refinitiv-dataplatform/
https://pypi.org/project/lseg-data/
 
Which one do you recommend to use?
 
And then given the recommended package, could you share some example code that initiates a session without need for a config file please?
 
For example, using the definitiv.dataplatform I have tried:
 
import refinitiv.dataplatform as rdp
grant = rdp.GrantPassword(username="cip@vitol.com", password=xyz)
 
rdp.open_platform_session(
    app_key="as generated on the workspace app",
    grant=grant,
)
 
 
But this give me a PlatformSessionError:
PlatformSessionError: Error code -1 | ERROR!!! response 400 while requesting URL('https://api.refinitiv.com/auth/oauth2/v1/token').
      {"error":"access_denied"  ,"error_description":"Invalid username or password." }
 
 
I have also tried refinitiv.data but this seems more involved:
 
import refinitiv.data as rd
grant = rd.session.platform.GrantPassword(username="cip@vitol.com", password=…)
definition = rd.session.platform.Definition(
    app_key="another api key",
    grant=grant,
    signon_control=False)
 
session = definition.get_session()
rd.open_session()
 
df = rd.get_data(
    universe=['USD=', 'EUR=', "LSEG.L"],
    fields=['BID', 'ASK', 'TR.Revenue']
)
 
 
Thank you for looking into this. 
Kind regards,
Denis