As programmers we don't want to reinvent the wheel so code use and using tested libraries/frameworks are in everyone's best interest (usually). However if you don't know that the "wheel" has been invented you don't know that you should look at library/framework X to help with your current problem.
Specially in Python if you were about to start a large project where would you go/research first to see if a solution to some of your requirements doesn't already exist. Obviously Google but do you have a system of steps you take when researching? Sites you check first, community sites you inquire with? Then having found a solution what steps do you take to make sure it "works" beyond running tests for it? If there are no tests does it instantly get removed from the maybe list?