select all groups a user belongs to in system tables

Hi,

I'm new to sql and postgres and I am trying to create a query that will
return the list of groups a user belongs to.

As the grolist column in pg_group is an array is there a simple way to
return the list?

I've checked the array documentation and according to that document the
pg_group table should be redesigned.

Any assistance would be welcome. Thanks in advanced.