Update lib.rs #2
                
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Use Result in add_message: Changed the return type of add_message to Result to handle errors more explicitly.
Better Input Validation: Added input validation for non-empty fields and a size check to prevent exceeding the maximum allowed size.
Logging Integration: Introduced logging statements to track message addition, updates, and deletions.
Parameterized Memory Sizes: Added a constant MAX_MESSAGE_SIZE to parameterize the maximum allowed size for a message.