Get geometry from layers (Python)

Hi I am trying to program in Python something like the geometry pipeline component where you can obtain all the geometry contained in a layer whose name contains a string of characters. 

Input: string of characters contained in the layer name.

Output: all the geometry contained in those layer(s). 

I tried this: 

import rhinoscriptsyntax as rs
import scriptcontext as sc
import Rhino as rh
import GhPython as gp

sc.doc = rh.RhinoDoc.ActiveDoc
layers = rs.LayerNames()
a = filter (lambda w: x in w, layers)

for i in a:
obj = sc.doc.Objects.FindByLayer(i)
b = obj

But I have not been able to make it work, it does not output the geometry elements.

Someone knows how to solve this?

Thanks in advance, 

Alejandro