import Rhino
import scriptcontext

# Prompt to select the set of polysurfaces to union
breps = Rhino.Input.RhinoGet.GetMultipleObjects("Select the set of polysurfaces to union", False, Rhino.DocObjects.ObjectType.Brep)

# Extract the breps from the object references
breps = [obj_ref.Brep() for obj_ref in breps[1]]

# Create the boolean union
union = Rhino.Geometry.Brep.CreateBooleanUnion(breps, scriptcontext.doc.ModelAbsoluteTolerance)

# Bake the union to the document
if union:
    for brep in union:
        scriptcontext.doc.Objects.AddBrep(brep)

import rhinoscriptsyntax as rs

# Prompt to select the set of polysurfaces to union
guids = rs.GetObjects("Select the set of polysurfaces to union", 16)

# Perform boolean union
union = rs.BooleanUnion(guids)