User turns:
user: Arrange a complete listing of all files and directories presently located here, making sure you don't overlook the hidden ones too.
user: Locate any document titled 'annual_report.txt' wherever it might be within this directory or its subdirectories.
user: What's inside?
user: Log my user id USR001 in, and relay a message to the ID 'USR002', updating them with what's inside verbatim as the body of the message.

Involved APIs: MessageAPI
GorillaFileSystem
Ground-truth function call path:
GorillaFileSystem.ls
GorillaFileSystem.find
GorillaFileSystem.cp
GorillaFileSystem.mv
GorillaFileSystem.grep
GorillaFileSystem.tail
MessageAPI.send_message