hs_unfold.py

import pymel.core as pm
import maya.mel as mel

# Get current selection
selected = pm.selected()

mel.eval("ConvertSelectionToUVs")

# Unfold, straighten, unfold
pm.u3dUnfold(selected, ite = 1, p = 0, bi = 1, tf = 1, ms = 1024, rs = 0)
mel.eval('texStraightenUVs "UV" 30')
pm.u3dUnfold(selected, ite = 1, p = 0, bi = 1, tf = 1, ms = 1024, rs = 0)

pm.hilite(pm.ls(hilite=True), r=True)    # Solves highlighting of UVs by highliging... whatever is highlighted?

# Select the previous selection and convert to UVShell.
pm.select(selected, r=True)
mel.eval("ConvertSelectionToUVShell")