regular expression for getting content between parentheses

[Rajanikanth Jammalamadaka]

Hi

I have a text file as follows:

testName = (
someParam = value1
anotherParam = (value2, value3)
)

how do I write a regular expression to get all the contents of the
file which are between the first and last parentheses.

In this case, I want:

someParam = value1
anotherParam = (value2, value3)

Thanks,

Raj