rm

• Usage: java gitlet.Main rm [file name]
• Description: Unstage the file if it is currently staged for addition. If the file is tracked in the current commit, stage it for removal and remove the file from the working directory if the user has not already done so (do not remove it unless it is tracked in the current commit).
• Runtime: Should run in constant time relative to any significant measure.
• Failure cases: If the file is neither staged nor tracked by the head commit, print the error message No reason to remove the file.
• Dangerous?: Yes (although if you use our utility methods, you will only hurt your repository files, and not all the other files in your directory.)
• Our line count: ~20