def readcomments(filename, comment='#'):
    """
    Reads in filename and extracts only data that contains the comments
    parameter.
    
    Reference
    ---------
    https://stackoverflow.com/a/39724905/8765762
    """
    comments_all = []
    with open(filename, 'r') as cmt_file:
        for line in cmt_file:
            if line[0] == comment:
                comments_all.append(line[1:])
    return comments_all
