A few things
1: Pull request feedback - in my job we peer review all pull request's for our team and I was not prepared for the kind of feedback I would get. Accepting feedback on something you made in code is learned for me and I was not used to other people looking at my code like this.
2: How strongly people feel about code formatting - I never thought that I'd see so many people so passionate about the placement of a bracket.
3: Assuming that everyone around me and people who were more experienced than I was knew everything about a given subject. Its important to take in information given to you by a superior or a seasoned developer but as long as you research that information to learn more about it.
I feel like all of my points here are just signs that I needed to grow up at some point in my career! But really that's what I wasn't ready for. I knew I would work long hours and I was ready for that. It's all the items above that I didn't expect.
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