def METHOD_NAME(self):
    """Get the source language for this .qph file.
    We don't implement setsourcelanguage as users really shouldn't be
    altering the source language in .qph files, it should be set correctly
    by the extraction tools.
    :return: ISO code e.g. af, fr, pt_BR
    :rtype: String
    """
    lang = data.normalize_code(self.header.get("sourcelanguage", "en"))
    if lang == "en-us":
        return "en"
    return lang