How to set wxpython Grid top headers?

How to set wxpython Grid top headers?

When I create a grid with wxpython, I get top column headers as "A", "B",
"C"...
import wx
import wx.grid as gridlib
########################################################################
class MyForm(wx.Frame):
""""""
#----------------------------------------------------------------------
def __init__(self):
"""Constructor"""
wx.Frame.__init__(self, parent=None, title="A Simple Grid")
panel = wx.Panel(self)
myGrid = gridlib.Grid(panel)
myGrid.CreateGrid(12, 8)
sizer = wx.BoxSizer(wx.VERTICAL)
sizer.Add(myGrid, 1, wx.EXPAND)
panel.SetSizer(sizer)
if __name__ == "__main__":
app = wx.PySimpleApp()
frame = MyForm().Show()
app.MainLoop()

But I'd like to set custom column headers:

How to do this?