def load_linelist(filename):
    """Load standard wavelength line list from a given file.

    Args:
        filename (str): Name of the wavelength standard list file.

    Returns:
        *list*: A list containing (wavelength, species).
    """
    linelist = []
    infile = open(filename)
    for row in infile:
        row = row.strip()
        if len(row)==0 or row[0] in '#%!@':
            continue
        g = row.split()
        wl = float(g[0])
        if len(g)>1:
            species = g[1]
        else:
            species = ''
        linelist.append((wl, species))
    infile.close()
    return linelist