From 696f4e41149a8f91e963d33e2f6ea9bc835f2260 Mon Sep 17 00:00:00 2001
From: Sergey M <dstftw@gmail.com>
Date: Tue, 1 Jan 2019 23:13:39 +0700
Subject: [PATCH] [README.md] Add more guide lines for regular expressions

---
 README.md | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index b3c39bf66..bdc5faeec 100644
--- a/README.md
+++ b/README.md
@@ -1133,11 +1133,33 @@ title = meta.get('title') or self._og_search_title(webpage)
 
 This code will try to extract from `meta` first and if it fails it will try extracting `og:title` from a `webpage`.
 
-### Make regular expressions flexible
+### Regular expressions
 
-When using regular expressions try to write them fuzzy and flexible.
+#### Don't capture groups you don't use
+
+Capturing group must be an indication that it's used somewhere in the code. Any group that is not used must be non capturing.
+
+##### Example
+
+Don't capture id attribute name here since you can't use it for anything anyway.
+
+Correct:
+
+```python
+r'(?:id|ID)=(?P<id>\d+)'
+```
+
+Incorrect:
+```python
+r'(id|ID)=(?P<id>\d+)'
+```
+
+
+#### Make regular expressions relaxed and flexible
+
+When using regular expressions try to write them fuzzy, relaxed and flexible, skipping insignificant parts that are more likely to change, allowing both single and double quotes for quoted values and so on.
  
-#### Example
+##### Example
 
 Say you need to extract `title` from the following HTML code: