solidity/test/libsolidity/syntaxTests/using/library_at_file_level.sol

library L {
    function externalFunction(uint) external pure {}
    function publicFunction(uint) public pure {}
    function internalFunction(uint) internal pure {}
}

using L for uint;

contract C {
    function f() public pure {
        uint x;
        x.externalFunction();
        x.publicFunction();
        x.internalFunction();
    }
}
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