--the second Term is expected to have "Variable" as it's value constructor
--the first Term value cannot contain the same variable as the second Term value
--when the first Term value is constructed by a "Function" value constructor.
------------------------------------------------------------------------------
foteSet2Subs :: FOTEset -> Substitution
foteSet2Subs = map swap
foteSet2Subs :: FOTEset -> Substitution
foteSet2Subs = map swap
foteSet2Subs = map swap