Adding file reading line by line in nim

Nim-for-Python-Programmers.md

@@ -209,4 +209,9 @@ See [this](http://rosettacode.org/wiki/Abstract_type#Nim)
 var is_happy = if has_cat(): "quite" else: "not much"
 ```
 
+### Reading files line by line
+``` Nim
+for line in lines "yourfile.txt":
+  echo line
+```