How to use the vscode-languageserver-types.DiagnosticSeverity function in vscode-languageserver-types

const errors = diags.map(d => {
                // Convert lines to zero-based to accomodate protocol
                const startPosition = types.Position.create(d.start.line - 1, d.start.offset - 1)
                const endPosition = types.Position.create(d.end.line - 1, d.end.offset - 1)
                const range = types.Range.create(startPosition, endPosition)

                const ret: types.Diagnostic = {
                    // type: null,
                    code: d.code,
                    message: d.text,
                    range,
                    severity: types.DiagnosticSeverity.Error,
                }
                return ret
            })

export function intoCode(type: Type): types.DiagnosticSeverity {
      switch (type) {
        case "env": return types.DiagnosticSeverity.Error;
        case "parser": return types.DiagnosticSeverity.Error;
        case "type": return types.DiagnosticSeverity.Error;
        case "unknown": return types.DiagnosticSeverity.Error;
        case "warning": return types.DiagnosticSeverity.Warning;
        default: throw new Error(`: ${type}`);
      }
    }
  }

export function intoCode(type: Type): types.DiagnosticSeverity {
      switch (type) {
        case "env": return types.DiagnosticSeverity.Error;
        case "parser": return types.DiagnosticSeverity.Error;
        case "type": return types.DiagnosticSeverity.Error;
        case "unknown": return types.DiagnosticSeverity.Error;
        case "warning": return types.DiagnosticSeverity.Warning;
        default: throw new Error(`: ${type}`);
      }
    }
  }

function translateSeverity(typescript, severity) {
    switch (severity) {
        case vscode.DiagnosticSeverity.Information:
        case vscode.DiagnosticSeverity.Hint:
            return typescript.DiagnosticCategory.Message;
        case vscode.DiagnosticSeverity.Warning:
            return typescript.DiagnosticCategory.Warning;
        case vscode.DiagnosticSeverity.Error:
        default:
            return typescript.DiagnosticCategory.Error;
    }
}
function toDisplayParts(text) {

function translateSeverity(
    typescript: typeof ts,
    severity: vscode.DiagnosticSeverity | undefined
): ts.DiagnosticCategory {
    switch (severity) {
        case vscode.DiagnosticSeverity.Information:
        case vscode.DiagnosticSeverity.Hint:
            return typescript.DiagnosticCategory.Message;

        case vscode.DiagnosticSeverity.Warning:
            return typescript.DiagnosticCategory.Warning;

        case vscode.DiagnosticSeverity.Error:
        default:
            return typescript.DiagnosticCategory.Error;
    }
}

function translateSeverity(severity) {
    switch (severity) {
        case vscode.DiagnosticSeverity.Information:
        case vscode.DiagnosticSeverity.Hint:
            return ts.DiagnosticCategory.Message;
        case vscode.DiagnosticSeverity.Warning:
            return ts.DiagnosticCategory.Warning;
        case vscode.DiagnosticSeverity.Error:
        default:
            return ts.DiagnosticCategory.Error;
    }
}
//# sourceMappingURL=styled-string-language-service.js.map

function toDiagnostic(marker) {
                var range = vscode_languageserver_types_1.Range.create(document.positionAt(marker.getOffset()), document.positionAt(marker.getOffset() + marker.getLength()));
                var source = document.languageId;
                return {
                    code: marker.getRule().id,
                    source: source,
                    message: marker.getMessage(),
                    severity: marker.getLevel() === nodes.Level.Warning ? vscode_languageserver_types_1.DiagnosticSeverity.Warning : vscode_languageserver_types_1.DiagnosticSeverity.Error,
                    range: range
                };
            }
            return entries.filter(function (entry) { return entry.getLevel() !== nodes.Level.Ignore; }).map(toDiagnostic);

function translateSeverity(severity) {
    switch (severity) {
        case vscode.DiagnosticSeverity.Information:
        case vscode.DiagnosticSeverity.Hint:
            return ts.DiagnosticCategory.Message;
        case vscode.DiagnosticSeverity.Warning:
            return ts.DiagnosticCategory.Warning;
        case vscode.DiagnosticSeverity.Error:
        default:
            return ts.DiagnosticCategory.Error;
    }
}
//# sourceMappingURL=styled-string-language-service.js.map

function translateSeverity(
    typescript: typeof ts,
    severity: vscode.DiagnosticSeverity | undefined
): ts.DiagnosticCategory {
    switch (severity) {
        case vscode.DiagnosticSeverity.Information:
        case vscode.DiagnosticSeverity.Hint:
            return typescript.DiagnosticCategory.Message;

        case vscode.DiagnosticSeverity.Warning:
            return typescript.DiagnosticCategory.Warning;

        case vscode.DiagnosticSeverity.Error:
        default:
            return typescript.DiagnosticCategory.Error;
    }
}

function translateSeverity(typescript, severity) {
    switch (severity) {
        case vscode.DiagnosticSeverity.Information:
        case vscode.DiagnosticSeverity.Hint:
            return typescript.DiagnosticCategory.Message;
        case vscode.DiagnosticSeverity.Warning:
            return typescript.DiagnosticCategory.Warning;
        case vscode.DiagnosticSeverity.Error:
        default:
            return typescript.DiagnosticCategory.Error;
    }
}
function toDisplayParts(text) {