protected virtual object EvalThenPart(ParseTree tree, params object[] paramlist)
 {
     throw new NotImplementedException();
 }
 protected virtual object EvalStart(ParseTree tree, params object[] paramlist)
 {
     return("Could not interpret input; no semantics implemented.");
 }
 protected virtual object EvalCompanyMatchedClause(ParseTree tree, params object[] paramlist)
 {
     throw new NotImplementedException();
 }
 protected virtual object EvalCreatePublicRequestClause(ParseTree tree, params object[] paramlist)
 {
     throw new NotImplementedException();
 }
 protected virtual object EvalAttachToProjectClause(ParseTree tree, params object[] paramlist)
 {
     throw new NotImplementedException();
 }
 protected virtual object EvalSubjectContainsClause(ParseTree tree, params object[] paramlist)
 {
     throw new NotImplementedException();
 }
 protected object GetValue(ParseTree tree, TokenType type, int index)
 {
     return(GetValue(tree, type, ref index));
 }