How to extract data from text file after searchstring

Hello,

i want to create an external file with some limits.

The file should be imported a teststart to globals.

In the limit teststeps i want to add a pre-expression that reads out the global and sets the limits.

The file looks like:

a_low=1.1

a_high=2.2

b_low=3.1

b_high=3.2

Currently i have a function that reads out the file content into a global string variable.

My question is:

Are there built in functions where i can pass this global variable + the name of a line (like "a_high) and it returns the numeric value behind it?

Thanks