code: function report(node) {
              context.report({
                  node,
                  message: "Unexpected var, use let or const instead.",
  
                  fix(fixer) {
                      const varToken = sourceCode.getFirstToken(node, { filter: t => t.value === "var" });
  
                      return canFix(node)
                          ? fixer.replaceText(varToken, "let")
                          : null;
                  }
              });
          }
docs: Reports a given variable declaration node.
  
  @param {ASTNode} node - A variable declaration node to report.
  @returns {void}