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string.format works like C's printf:

print(string.format("%d + %d = %d", 2, 3, 5))
print(string.format("%.2f", math.pi))     -- 3.14
print(string.format("%-10s|%5d", "hi", 42))  -- left-pad string, right-pad number

Common specifiers:

• %d integer
• %f float (%.2f for 2 decimals)
• %s string
• %x hex
• %q quoted string (escaped for re-parsing by Lua)

Unlike Python f-strings, Lua's %s will call tostring() on whatever you pass — handy for debugging.