206 lines
		
	
	
		
			7.0 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			206 lines
		
	
	
		
			7.0 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
/**
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 * @fileoverview Rule to disallow unsafe optional chaining
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 * @author Yeon JuAn
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 */
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"use strict";
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const UNSAFE_ARITHMETIC_OPERATORS = new Set(["+", "-", "/", "*", "%", "**"]);
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const UNSAFE_ASSIGNMENT_OPERATORS = new Set(["+=", "-=", "/=", "*=", "%=", "**="]);
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const UNSAFE_RELATIONAL_OPERATORS = new Set(["in", "instanceof"]);
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/**
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 * Checks whether a node is a destructuring pattern or not
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 * @param {ASTNode} node node to check
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 * @returns {boolean} `true` if a node is a destructuring pattern, otherwise `false`
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 */
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function isDestructuringPattern(node) {
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    return node.type === "ObjectPattern" || node.type === "ArrayPattern";
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}
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/** @type {import('../shared/types').Rule} */
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module.exports = {
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    meta: {
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        type: "problem",
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        docs: {
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            description: "Disallow use of optional chaining in contexts where the `undefined` value is not allowed",
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            recommended: true,
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            url: "https://eslint.org/docs/latest/rules/no-unsafe-optional-chaining"
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        },
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        schema: [{
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            type: "object",
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            properties: {
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                disallowArithmeticOperators: {
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                    type: "boolean",
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                    default: false
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                }
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            },
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            additionalProperties: false
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        }],
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        fixable: null,
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        messages: {
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            unsafeOptionalChain: "Unsafe usage of optional chaining. If it short-circuits with 'undefined' the evaluation will throw TypeError.",
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            unsafeArithmetic: "Unsafe arithmetic operation on optional chaining. It can result in NaN."
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        }
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    },
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    create(context) {
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        const options = context.options[0] || {};
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        const disallowArithmeticOperators = (options.disallowArithmeticOperators) || false;
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        /**
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         * Reports unsafe usage of optional chaining
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         * @param {ASTNode} node node to report
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         * @returns {void}
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         */
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        function reportUnsafeUsage(node) {
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            context.report({
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                messageId: "unsafeOptionalChain",
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                node
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            });
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        }
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        /**
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         * Reports unsafe arithmetic operation on optional chaining
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         * @param {ASTNode} node node to report
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         * @returns {void}
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         */
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        function reportUnsafeArithmetic(node) {
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            context.report({
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                messageId: "unsafeArithmetic",
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                node
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            });
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        }
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        /**
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         * Checks and reports if a node can short-circuit with `undefined` by optional chaining.
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         * @param {ASTNode} [node] node to check
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         * @param {Function} reportFunc report function
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         * @returns {void}
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         */
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        function checkUndefinedShortCircuit(node, reportFunc) {
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            if (!node) {
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                return;
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            }
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            switch (node.type) {
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                case "LogicalExpression":
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                    if (node.operator === "||" || node.operator === "??") {
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                        checkUndefinedShortCircuit(node.right, reportFunc);
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                    } else if (node.operator === "&&") {
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                        checkUndefinedShortCircuit(node.left, reportFunc);
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                        checkUndefinedShortCircuit(node.right, reportFunc);
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                    }
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                    break;
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                case "SequenceExpression":
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                    checkUndefinedShortCircuit(
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                        node.expressions[node.expressions.length - 1],
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                        reportFunc
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                    );
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                    break;
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                case "ConditionalExpression":
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                    checkUndefinedShortCircuit(node.consequent, reportFunc);
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                    checkUndefinedShortCircuit(node.alternate, reportFunc);
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                    break;
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                case "AwaitExpression":
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                    checkUndefinedShortCircuit(node.argument, reportFunc);
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                    break;
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                case "ChainExpression":
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                    reportFunc(node);
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                    break;
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                default:
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                    break;
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            }
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        }
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        /**
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         * Checks unsafe usage of optional chaining
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         * @param {ASTNode} node node to check
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         * @returns {void}
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         */
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        function checkUnsafeUsage(node) {
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            checkUndefinedShortCircuit(node, reportUnsafeUsage);
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        }
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        /**
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         * Checks unsafe arithmetic operations on optional chaining
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         * @param {ASTNode} node node to check
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         * @returns {void}
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         */
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        function checkUnsafeArithmetic(node) {
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            checkUndefinedShortCircuit(node, reportUnsafeArithmetic);
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        }
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        return {
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            "AssignmentExpression, AssignmentPattern"(node) {
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                if (isDestructuringPattern(node.left)) {
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                    checkUnsafeUsage(node.right);
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                }
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            },
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            "ClassDeclaration, ClassExpression"(node) {
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                checkUnsafeUsage(node.superClass);
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            },
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            CallExpression(node) {
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                if (!node.optional) {
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                    checkUnsafeUsage(node.callee);
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                }
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            },
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            NewExpression(node) {
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                checkUnsafeUsage(node.callee);
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            },
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            VariableDeclarator(node) {
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                if (isDestructuringPattern(node.id)) {
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                    checkUnsafeUsage(node.init);
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                }
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            },
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            MemberExpression(node) {
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                if (!node.optional) {
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                    checkUnsafeUsage(node.object);
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                }
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            },
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            TaggedTemplateExpression(node) {
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                checkUnsafeUsage(node.tag);
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            },
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            ForOfStatement(node) {
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                checkUnsafeUsage(node.right);
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            },
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            SpreadElement(node) {
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                if (node.parent && node.parent.type !== "ObjectExpression") {
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                    checkUnsafeUsage(node.argument);
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                }
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            },
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            BinaryExpression(node) {
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                if (UNSAFE_RELATIONAL_OPERATORS.has(node.operator)) {
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                    checkUnsafeUsage(node.right);
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                }
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                if (
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                    disallowArithmeticOperators &&
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                    UNSAFE_ARITHMETIC_OPERATORS.has(node.operator)
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                ) {
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                    checkUnsafeArithmetic(node.right);
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                    checkUnsafeArithmetic(node.left);
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                }
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            },
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            WithStatement(node) {
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                checkUnsafeUsage(node.object);
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            },
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            UnaryExpression(node) {
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                if (
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                    disallowArithmeticOperators &&
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                    UNSAFE_ARITHMETIC_OPERATORS.has(node.operator)
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                ) {
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                    checkUnsafeArithmetic(node.argument);
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                }
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            },
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            AssignmentExpression(node) {
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                if (
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                    disallowArithmeticOperators &&
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                    UNSAFE_ASSIGNMENT_OPERATORS.has(node.operator)
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                ) {
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                    checkUnsafeArithmetic(node.right);
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                }
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            }
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        };
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    }
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};
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