def load_mapping(mapping_txt):
    """Load mapping file

    Parameter
    ---------
    mapping_txt : `str`
        Path to mapping file

    Returns
    -------
    mapping : `dict`
        {1st field: 2nd field} dictionary
    """

    with open(mapping_txt, mode='r') as fp:
        lines = fp.readlines()

    mapping = dict()
    for line in lines:
        key, value, *left = line.strip().split()
        mapping[key] = value

    return mapping