How to use the vscode-languageserver-protocol.DiagnosticSeverity.Information function in vscode-languageserver-protocol

this.reportStyleCheckAsWarnings &&
      this.isStyleCheckDiagnostic(diagnostic.code) &&
      diagnostic.category === PConst.DiagnosticCategory.error
    ) {
      return DiagnosticSeverity.Warning
    }

    switch (diagnostic.category) {
      case PConst.DiagnosticCategory.error:
        return DiagnosticSeverity.Error

      case PConst.DiagnosticCategory.warning:
        return DiagnosticSeverity.Warning

      case PConst.DiagnosticCategory.suggestion:
        return DiagnosticSeverity.Information

      default:
        return DiagnosticSeverity.Error
    }
  }

diagnostics.forEach(diagnostic => {
      let { source, code, severity, message } = diagnostic
      let s = getSeverityName(severity)[0]
      let str = `[${source}${code ? ' ' + code : ''}] [${s}] ${message}`
      let filetype = 'Error'
      if (ft === '') {
        switch (diagnostic.severity) {
          case DiagnosticSeverity.Hint:
            filetype = 'Hint'
            break
          case DiagnosticSeverity.Warning:
            filetype = 'Warning'
            break
          case DiagnosticSeverity.Information:
            filetype = 'Info'
            break
        }
      } else {
        filetype = ft
      }
      docs.push({ filetype, content: str })
    })
    if (useFloat) {

public setDiagnosticInfo(bufnr: number, diagnostics: ReadonlyArray): void {
    let lnums = [0, 0, 0, 0]
    let info = { error: 0, warning: 0, information: 0, hint: 0, lnums }
    for (let diagnostic of diagnostics) {
      switch (diagnostic.severity) {
        case DiagnosticSeverity.Warning:
          info.warning = info.warning + 1
          lnums[1] = lnums[1] || diagnostic.range.start.line + 1
          break
        case DiagnosticSeverity.Information:
          info.information = info.information + 1
          lnums[2] = lnums[2] || diagnostic.range.start.line + 1
          break
        case DiagnosticSeverity.Hint:
          info.hint = info.hint + 1
          lnums[3] = lnums[3] || diagnostic.range.start.line + 1
          break
        default:
          lnums[0] = lnums[0] || diagnostic.range.start.line + 1
          info.error = info.error + 1
      }
    }
    this.nvim.call('coc#util#set_buf_var', [this.bufnr, 'coc_diagnostic_info', info], true)
    if (bufnr == this.bufnr) {
      this.nvim.call('coc#util#do_autocmd', ['CocDiagnosticChange'], true)
    }

this.reportStyleCheckAsWarnings &&
      this.isStyleCheckDiagnostic(diagnostic.code) &&
      diagnostic.category === PConst.DiagnosticCategory.error
    ) {
      return DiagnosticSeverity.Warning
    }

    switch (diagnostic.category) {
      case PConst.DiagnosticCategory.error:
        return DiagnosticSeverity.Error

      case PConst.DiagnosticCategory.warning:
        return DiagnosticSeverity.Warning

      case PConst.DiagnosticCategory.suggestion:
        return DiagnosticSeverity.Information

      default:
        return DiagnosticSeverity.Error
    }
  }

export function getSeverityName(severity: DiagnosticSeverity): string {
  switch (severity) {
    case DiagnosticSeverity.Error:
      return 'Error'
    case DiagnosticSeverity.Warning:
      return 'Warning'
    case DiagnosticSeverity.Information:
      return 'Information'
    case DiagnosticSeverity.Hint:
      return 'Hint'
    default:
      return 'Error'
  }
}

this.client.diagnosticsManager.diagnosticsReceived(diagnosticsKind, file.toString(), diagnostics.filter(diag => {
      if (!reportUnnecessary) {
        diag.tags = undefined
        if (diag.reportUnnecessary && diag.severity === DiagnosticSeverity.Information) {
          return false
        }
      }
      return true
    }))
  }