How to create a new operator inpg for spec data type?

[jack...@gmail.com]

I need to create a new operator like '<->' and its syntax is that text1 <-> 
text2,
for the usage like this: 'a' <-> 'b' = 'a1b1', so how could I realize this one?
Can you give me some exmaples.

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jack...@gmail.com