def __strip_line(input_file):
    """
    Removes spaces and newline whitespaces.

    Parameters
    ----------
    input_file : file
        .seq file

    Returns
    -------
    line : str
        First line in input_file after removing spaces and newline whitespaces. Note: File pointer is remembered,
        so successive calls work as expected. Returns -1 for eof.
    """
    line = input_file.readline()
    return line.strip() if line != '' else -1
