def _read_header(filename):
    """Read the text header for each file

    Parameters
    ----------
    channel_file : Path
        path to single filename with the header

    Returns
    -------
    dict
        header
    """
    with filename.open('rb') as f:
        h = f.read(HDR_LENGTH).decode()

        header = {}
        for line in h.split('\n'):
            if '=' in line:
                key, value = line.split(' = ')
                key = key.strip()[7:]
                value = value.strip()[:-1]
                header[key] = value

    return header