The phrase "do by" is a verb phrase that means to treat someone or something in a certain way. It often implies an action or behavior towards a person or situation, usually with a sense of fairness or caution.
In more advanced contexts, "do by" can imply a moral obligation or responsibility to treat others well.
Do Right By: To treat someone fairly or properly.
Do Someone Dirty: To treat someone unfairly or dishonestly.
In summary, "do by" is about how you treat others and implies a level of responsibility in that treatment, whether it’s positive or cautious.