def read_molfile_v2000(lr):
    """Reads a single V2000 molfile and returns it as a tuple containing
individual lines."""
    molfile = []
    line = ''
    while not lr.eof and line != 'M  END' and line[:6] != '$DTYPE':
        line = lr.get_line()
        # We need to deal with empty molfiles after $DATUM $MFMT or ones
        # without "M  END".
        if line and line[:6] == '$DTYPE':
            break
        molfile.append(line)
    if line[:6] == '$DTYPE':
        lr.unget_line()
    return tuple(molfile)