code: function isSymbolTerm(node, symbolName) {
    if (Node.PolynomialTerm.isPolynomialTerm(node)) {
      const polyTerm = new Node.PolynomialTerm(node);
      if (polyTerm.getSymbolName() === symbolName) {
        return true;
      }
    }
    return false;
  }
docs: Returns if `node` is a polynomial term with symbol `symbolName`