def convert_to_float(token):
    """
    Convert token to float.
    Args:
        token (str): a string token to convert to float
    Returns:
        float if the token can be converted, otherwise the token
    """
    if token == '':
        return None
    try:
        float(token.replace(',', ''))
        return float(token.replace(',', ''))
    except ValueError:
        return token
