title: No method prog() to build a ParseTree object
body: <p>I experience issues with ANTLR 4, using the visitor classes.
  I try to write the following code:</p>
  
  <pre><code>import bla.gen.InputLexer;
  import bla.gen.InputParser;
  import org.antlr.v4.runtime.ANTLRFileStream;
  import org.antlr.v4.runtime.CommonTokenStream;
  import org.antlr.v4.runtime.tree.ParseTree;
  
  public class Main {
      public static void main(String[] args) throws Exception {
          InputLexer lexer = new InputLexer(new ANTLRFileStream("pl_example.lp"));
          InputParser parser = new InputParser(new CommonTokenStream(lexer));
          parser.setBuildParseTree(true);
          ParseTree tree = parser.prog();
          ParserVisitor visitor = new ParserVisitor();
          visitor.visit();
  
      }
  }
  </code></pre>
  
  <p>I try to mimic the code found in the book example here: 
  <a href="https://pragprog.com/titles/tpantlr2/source_code" rel="nofollow">https://pragprog.com/titles/tpantlr2/source_code</a></p>
  
  <p>(I have no access to the book, just the examples).</p>
  
  <p>But I've got an error because the method parser.prog() does not exists...</p>
  
  <p>I use ANTLR 4.5.</p>
  
  <p>Do you know how to generate ParseTree with this version?</p>