Python Startup: Font Size trick on rxvt

.bashrc

@@ -68,6 +68,8 @@ alias ls='ls --color=auto'
 alias fingerprint='find /etc/ssh -name "*.pub" -exec ssh-keygen -l -f {} \;'
 alias rekey='ssh-add -e /usr/lib/x86_64-linux-gnu/opensc-pkcs11.so; ssh-add -s /usr/lib/x86_64-linux-gnu/opensc-pkcs11.so'
 
+export PYTHONSTARTUP=$HOME/.config/pythonstartup.py
+
 for extra in /etc/bash_completion ~/.bash_aliases ~/.my_bashrc ~/.git-prompt.sh
 do
     if [ -f "$extra" ]

.config/pythonstartup.py

@@ -0,0 +1,16 @@
+class FontSize:
+    def __init__(self):
+        self.font_size = 20
+
+    def __iadd__(self, x):
+        self.font_size += x
+        print(f"\33]50;xft:LiberationMono:size={self.font_size}\007")
+        return self
+
+    def __isub__(self, x):
+        self.font_size -= x
+        print(f"\33]50;xft:LiberationMono:size={self.font_size}\007")
+        return self
+
+
+font_size = FontSize()