💁♂️: A special placeholder value used in programming like -1 or 999 to represent termination or null values
🤔: One should be very careful choosing a sentinel value that is unique in form and won't naturally appear in data or algorithm, for this reason it is also sometimes called "elephant in Cairo"
# Go to Africa. # Put an elephant in Cairo. # Start at the Cape of Good Hope. # Work northward in an orderly manner, traversing the continent alternately east and west, # During each traverse pass: # Catch each animal seen. # Compare each animal caught to a known elephant. # Stop when a match is detected. # If you are in Cairo, then there are no elephants in Africa (other than the one you placed there).