virtual bool IsInRing()
Return the Boolean ``in ring'' property of a bond. The default value is
false. The ``in ring'' property of an bond may be set using the
OEBondBase::SetInRing
method. The ``in ring'' properties of bonds
and atoms are typically set by calling OEChem's
OEFindRingAtomsAndBonds
function. This is a stored, not a computed,
property.