internal override int VisitTrue(TrueExpr <T_Identifier> expression) { return(0); }
internal override BoolExpr <T_Identifier> VisitTrue(TrueExpr <T_Identifier> expression) { return(expression); }
internal override Vertex VisitTrue(TrueExpr <T_Identifier> expression) { return(Vertex.One); }
internal abstract T_Return VisitTrue(TrueExpr <T_Identifier> expression);
internal override BoolExpr <T_To> VisitTrue(TrueExpr <T_From> expression) { return(TrueExpr <T_To> .Value); }
internal override bool VisitTrue(TrueExpr <T_Identifier> expression) { return(true); }