How can i get Geom_Surface's UV parametric surface function?

[NFYG]

def read_step(filepath):

    compound = read_step_file(filepath)
   
    topo = TopologyExplorer(compound)

    
    for i,face in enumerate( topo.faces() ):

        geom_surface = BRep_Tool().Surface(face)

        print(geom_surface.Bounds())

I use such code to access every face of my *.STEP file.

How can i get geom_surface's UV parametric surface function?

And why the surface is infinite while my *.STEP file is finite and bounded? （geom_surface.Bounds() return infinite U1 U2 V1 V2）