Preserving Informations

Informations preserved by Damodar Rajbhandari

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  • No pdf view in emacs -nw. But works perfectly fine in emacs gui. pdf-tools won’t work in emacs -nw i.e. emacs in terminal mode. But you can do view it as text form by doing this M-x doc-view-mode.


  • Beamer Tutorial at here!


Python 3

  • Use constructor from Base(i.e. Parant) class in the Child class, along with child’s constructor.
    class a:
      def __init__(self,x):
          self.x = x    
      def se(self,z):
    class b(a):
      def __init__(self,x,y):
          self.y = y

We can use Base class methods(i.e. functions) by doing this:


We can call constructor of Parant class by doing this:


We can call constructor of Child class by doing this:

  • Merging two dictionaries in Python 3.x
d1 = {"a":1, "b":2}
d2 = {"c":3, "d":4}
d1Ud2 = {**d1, **d2}
>>> d1Ud2
{"a":1, "b":2, "c":3, "d":4}
  • Circular Dependencies

I strongly suggest to see “NameError while calling the parent class method from another module” for more details.

  • Install package from github
    pip install git+
  • Function annotation

This allows us to attach metadata to functions describing their parameters and return values. Read at PEP 3107 For example:

>>> def kinetic_energy(m:'in KG', v:'in M/S')->'Joules': 
        return 1/2*m*v**2
>>> kinetic_energy.__annotations__
{'return': 'Joules', 'v': 'in M/S', 'm': 'in KG'}
>>> '{:,} {}'.format(kinetic_energy(20,3000), kinetic_energy.__annotations__['return'])
'90,000,000.0 Joules'


  • Over riding the comments count by Disqus count in wordpress site
    <a href="<?php the_permalink() ?>#disqus_thread">Comments</a>
  • Dynamic copyright date
    &copy; 2017 – <?php echo date('Y'); ?>
  • Updating or installing plugin/theme got “to perform the requested action wordpress needs to access your web server. please enter your ftp”. Usually get when you install wordpress in localhost or server.
    $ sudo chown www-data:www-data /var/www/html/YourWordpressFolder -R
    $ sudo systemctl reload YourWebServer
  • Enable curl php in Ubuntu
    $ sudo apt-get install php-curl
    $ sudo service apache2 restart

Google Collab

  • Accessing file from Google drive
    from google.colab import drive
  • View LaTeX in notebook
    from IPython.display import Math, HTML
    display(HTML("<script src='"
    Math(r'F(k) = \int_{-\infty}^{\infty} f(x) e^{2\pi i k} dx')
  • Install LaTeX
    !sudo apt-get update
    !sudo apt-get install texlive-full
    !sudo apt install texlive-latex-base 
    !sudo apt install texlive-fonts-extra
  • Install Manim
  1. Install latex

  2. Install cairo, latex, ffmpeg, and sox by doing these:
    !sudo apt-get install ffmpeg
    !sudo apt-get install sox
    !sudo apt-get install libcairo2-dev libjpeg-dev libgif-dev python3-dev libffi-dev
    !python3 -m pip install pyreadline
    !python3 -m pip install pydub
    !python3 -m pip install pycairo
    !pip install -r requirements.txt
  3. Clone Manim library
    !git clone
  4. Checking!
    !cd manim
    !python3 -m manim SquareToCircle -pl
    !python3 -m manim OpeningManimExample -pl

    Any issues see this Manim Tutorial.

  • Writing python file from Google collab notebook
    # Write your python code below
  • Viewing the working directory
  • Accessing and run python file