Python: How to replace a character in a XML file with a new node?

I want to replace all instances of semicolon ":" in my node below with a new node "<colon/>" as shown below.

I want this:

<shortName>Trigger:Digital Edge:Source</shortName>

to become like this:

<shortName>Trigger<colon/>Digital Edge<colon/>Source</shortName>

I have already tried using search and replace string, but when I get the output all the "< >" change to &lt and &gt . Can anyone please suggest any techniques to do this. Thank You