def process_tex(lines):
    """
    Remove unnecessary section titles from the LaTeX file.

    """
    new_lines = []
    for line in lines:
        if (line.startswith(r'\section{numpy_demo.')
            or line.startswith(r'\subsection{numpy_demo.')
            or line.startswith(r'\subsubsection{numpy_demo.')
            or line.startswith(r'\paragraph{numpy_demo.')
            or line.startswith(r'\subparagraph{numpy_demo.')
            ):
            pass # skip!
        else:
            new_lines.append(line)
    return new_lines