ASTNode testNode = ASTNode.parseFormula(formula);
System.out.println("===================");
System.out.printf("[IN]:\t%s\n", formula);
System.out.printf("[OUT]:\t%s\n", testNode.toFormula());
System.out.printf("[LTX]:\t%s\n", testNode.toLaTeX());
// AssignmentRule as = new AssignmentRule(2, 4);
Model m = new Model(2, 4);
FunctionDefinition fd = new FunctionDefinition("f", 2, 4);
m.addFunctionDefinition(fd);