#    The contents of "ToolbarButtonPackage/__init__.py" is
#    identical to the first section of code in "Toolbar Buttons".
#
#    .. "ToolbarButtonPackage/__init__.py" ToolbarButtonPackage/__init__.py
#    .. "Toolbar Buttons" ToolbarButton.html

def mainchain():
    import re
    from chimera import openModels, Molecule

    mainChain = re.compile("^(N|CA|C)$", re.I)
    for m in openModels.list(modelTypes=[Molecule]):
        for a in m.atoms:
            a.display = mainChain.match(a.name) != None