My issue with learning codebases is when there is no documentation on what can be passed through as variables in an API. I mean it's fantastic my coworker wrote

My issue with learning codebases is when there is no documentation on what can be passed through as variables in an API. I mean it's fantastic my coworker wrote something to simplify REST retrievals for us, but what format is "string oldDate" in? Is it YYYY-mm-DD? mm/DD? I really hate learning APIs if there is no example of how it can be used. Microsoft has done a stellar job on their documentation but it still isn't enough at times. The "just do it" or "it just works" mentality with code is the #1 thing I hate when using other people's code. Half the time I have to read stuff directly out of their own codebases and actually run it to even figure it out. All because they were too lazy to write a comment somewhere to say "an example of this variable is: ...". In theory, I should be able to use your code right away, not pick at it for hours and go "ohhhh now I see."