-- Check if a expression is an implies expression.
isImpliesExpression :: FeatureExpression -> Bool
isImpliesExpression (Or (Not e1) (e2)) = True
isImpliesExpression :: FeatureExpression -> Bool
isImpliesExpression (Or (Not e1) (e2)) = True
isImpliesExpression (Or (Not e1) (e2)) = True