'string' does not contain a definition for 'IsEmpty' and no accessible extension method 'IsEmpty' accepting a first argument of type 'string' could be found (are you missing a using directive or an assembly reference?)

'Nonterminal' does not contain a definition for 'HasValue' and no accessible extension method 'HasValue' accepting a first argument of type 'Nonterminal' could be found (are you missing a using directive or an assembly reference?)

'string' does not contain a definition for 'IsEmpty' and no accessible extension method 'IsEmpty' accepting a first argument of type 'string' could be found (are you missing a using directive or an assembly reference?)

'string' does not contain a definition for 'IsEmpty' and no accessible extension method 'IsEmpty' accepting a first argument of type 'string' could be found (are you missing a using directive or an assembly reference?)

'string' does not contain a definition for 'IsEmpty' and no accessible extension method 'IsEmpty' accepting a first argument of type 'string' could be found (are you missing a using directive or an assembly reference?)

'TokenSymbol' does not contain a definition for 'HasValue' and no accessible extension method 'HasValue' accepting a first argument of type 'TokenSymbol' could be found (are you missing a using directive or an assembly reference?)

'TokenSymbol' does not contain a definition for 'HasValue' and no accessible extension method 'HasValue' accepting a first argument of type 'TokenSymbol' could be found (are you missing a using directive or an assembly reference?)

'TokenSymbol' does not contain a definition for 'HasValue' and no accessible extension method 'HasValue' accepting a first argument of type 'TokenSymbol' could be found (are you missing a using directive or an assembly reference?)

'Nonterminal' does not contain a definition for 'HasValue' and no accessible extension method 'HasValue' accepting a first argument of type 'Nonterminal' could be found (are you missing a using directive or an assembly reference?)

Process completed with exit code 134.

'string' does not contain a definition for 'IsEmpty' and no accessible extension method 'IsEmpty' accepting a first argument of type 'string' could be found (are you missing a using directive or an assembly reference?)

'Nonterminal' does not contain a definition for 'HasValue' and no accessible extension method 'HasValue' accepting a first argument of type 'Nonterminal' could be found (are you missing a using directive or an assembly reference?)

'string' does not contain a definition for 'IsEmpty' and no accessible extension method 'IsEmpty' accepting a first argument of type 'string' could be found (are you missing a using directive or an assembly reference?)

'string' does not contain a definition for 'IsEmpty' and no accessible extension method 'IsEmpty' accepting a first argument of type 'string' could be found (are you missing a using directive or an assembly reference?)

'string' does not contain a definition for 'IsEmpty' and no accessible extension method 'IsEmpty' accepting a first argument of type 'string' could be found (are you missing a using directive or an assembly reference?)

'TokenSymbol' does not contain a definition for 'HasValue' and no accessible extension method 'HasValue' accepting a first argument of type 'TokenSymbol' could be found (are you missing a using directive or an assembly reference?)

'TokenSymbol' does not contain a definition for 'HasValue' and no accessible extension method 'HasValue' accepting a first argument of type 'TokenSymbol' could be found (are you missing a using directive or an assembly reference?)

'TokenSymbol' does not contain a definition for 'HasValue' and no accessible extension method 'HasValue' accepting a first argument of type 'TokenSymbol' could be found (are you missing a using directive or an assembly reference?)

'Nonterminal' does not contain a definition for 'HasValue' and no accessible extension method 'HasValue' accepting a first argument of type 'Nonterminal' could be found (are you missing a using directive or an assembly reference?)

'string' does not contain a definition for 'IsEmpty' and no accessible extension method 'IsEmpty' accepting a first argument of type 'string' could be found (are you missing a using directive or an assembly reference?)

Complete the task associated to this 'TODO' comment. (https://rules.sonarsource.com/csharp/RSPEC-1135)

Complete the task associated to this 'TODO' comment. (https://rules.sonarsource.com/csharp/RSPEC-1135)

Complete the task associated to this 'TODO' comment. (https://rules.sonarsource.com/csharp/RSPEC-1135)

Dispose 'stack' when it is no longer needed. (https://rules.sonarsource.com/csharp/RSPEC-2930)

Remove the unused private field '_x'. (https://rules.sonarsource.com/csharp/RSPEC-1144)

'ISpanFormattable' implements 'IFormattable' so 'IFormattable' can be removed from the inheritance list. (https://rules.sonarsource.com/csharp/RSPEC-1939)

Make 'InitialState' a static property. (https://rules.sonarsource.com/csharp/RSPEC-2325)

Loop should be simplified by calling Select(action => action.Key)) (https://rules.sonarsource.com/csharp/RSPEC-3267)

Refactor this method to reduce its Cognitive Complexity from 30 to the 15 allowed. (https://rules.sonarsource.com/csharp/RSPEC-3776)