ch - About some Small Functions

The solution to some common problems is proposed, as well as a summary of some small functions. In particular, it provides a useful function for some problems in chemistry. For example, monoa(), monob() and mono() function can be used to calculate The pH of weak acid/base. The ggpng() function can save the PNG format with transparent background. The period_table() function will show the periodic table. Also the show_ruler() function will show the ruler. The show_color() function is funny and easier to show colors. I also provide the symb() function to generate multiple symbols at once. The csv2vcf() function provides an easy method to generate a file. The sym2poly() and sym2coef() function can extract coefficients from polynomials.