extracting data sets from imported .shp file in python grasshopper

Hello,

I am a novice python programmer and I am hoping someone can please spare a sec to help me out?? I am importing a .shp file with @it plugin but I want to be able to manipulate this data through a custom python script. ideally the code will search through the .shp file and identify only the RELHMAX data set for further manipulation.

This is what the .shp data looks like https://drive.google.com/file/d/0BySL_YFrwgAuTTAzeVlacFdFXzA/view?u...

I am only interested in the RELHMAX data.

so far this is what I am doing but I want a=RELHMAX only