Remove some of the vertical whitespaces
Add a space after the end of the sentence:
	"A solution is a vector of natural numbers."
Add a space
Replace the code for `ordering()` with more neat code as suggested
by thisch (Thomas Hisch).

Link to the comment: https://github.com/sympy/sympy/pull/7241/files#r11232090
Merge branch 'solving_system_of_lde' of https://github.com/thilinarmtb/sympy into solving_system_of_lde