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contracts...1_Storage.sol

// SPDX-License-Identifier: GPL-3.0
// Use Solidity version between 0.7 and 0.9
pragma solidity >=0.7.0 <0.9.0;

/**
 * @title Storage
 * @dev Store & retrieve value in a variable
 */
contract Storage {
    // Defining the variable
    uint256 number;

    /**
     * @dev Store value in variable
     * @param num value to store
     */
    function storeNumber(uint256 num) public {
        number = num;
    }

    /**
     * @dev Return value 
     * @return value of 'number'
     */
    function retrieveNumber() public view returns (uint256){
        return number;
    }
}

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