def f01_15_listConvert2d1d(inputList):
    """
    Converting 2d list into 1d list
    E.g.
        [[1,2],[3,4]] -> [1,2,3,4]

    Parameters
    ----------
    l : list
        Two-dimentional list (can be empty)

    Returns
    -------
    r : list
        One-dimentional list
    """
    outputList = []
    for i in inputList:
        for j in i:
            outputList.append(j)
    return outputList


