def read_header(filename, comment_char="#"):
    """Read the header from a file

    Returns
    -------
    List[str]

    """
    header = []
    with open(filename, "r") as f:
        while True:
            line = f.readline()
            if line.startswith(comment_char) or line.isspace():
                header.append(line)
            else:
                break
    return header