def check_df_dict(df_dict):
    """
    Verify if the dictionary that needs to be transferred to a Pandas DataFrame
    makes sense

    Returns
    -------

    collens : dict
        Dictionary with df_dict keys as keys, len(df_dict[key]) as column.
        In other words: the length of each column (=rows) of the soon to be df.
    """
    collens = {}
    for col, values in df_dict.items():
        print('%6i : %s' % (len(values), col))
        collens[col] = len(values)
    return collens
