def is_classic_netcdf(file_buffer):
    """
    Returns True if the contents of the byte array matches the magic number in
    netCDF files

    :param str file_buffer: Byte-array of the first 4 bytes of a file
    """
    # CDF.
    if file_buffer == b"\x43\x44\x46\x01":
        return True
    return False