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This can be used e.g. to track the number\n * of elements in a mapping, issuing ERC721 ids, or counting request ids.\n *\n * Include with `using Counters for Counters.Counter;`\n * Since it is not possible to overflow a 256 bit integer with increments of one, `increment` can skip the {SafeMath}\n * overflow check, thereby saving gas. This does assume however correct usage, in that the underlying `_value` is never\n * directly accessed.\n */\nlibrary Counters {\n using SafeMath for uint256;\n\n struct Counter {\n // This variable should never be directly accessed by users of the library: interactions must be restricted to\n // the library's function. 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This can be used e.g. to track the number\n of elements in a mapping, issuing ERC721 ids, or counting request ids.\n Include with `using Counters for Counters.Counter;`\n Since it is not possible to overflow a 256 bit integer with increments of one, `increment` can skip the {SafeMath}\n overflow check, thereby saving gas. 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This can be used e.g. to track the number\n of elements in a mapping, issuing ERC721 ids, or counting request ids.\n Include with `using Counters for Counters.Counter;`\n Since it is not possible to overflow a 256 bit integer with increments of one, `increment` can skip the {SafeMath}\n overflow check, thereby saving gas. 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"updatedAt": "2020-08-12T09:47:18.549Z", "devdoc": { "author": "Matt Condon (@shrugs)", "details": "Provides counters that can only be incremented or decremented by one. This can be used e.g. to track the number of elements in a mapping, issuing ERC721 ids, or counting request ids. Include with `using Counters for Counters.Counter;` Since it is not possible to overflow a 256 bit integer with increments of one, `increment` can skip the {SafeMath} overflow check, thereby saving gas. This does assume however correct usage, in that the underlying `_value` is never directly accessed.", "kind": "dev", "methods": {}, "title": "Counters", "version": 1 }, "userdoc": { "kind": "user", "methods": {}, "version": 1 } }