public override async Task WriteStartElementAsync(string prefix, string localName)
{
await WriteByteAsync('<').ConfigureAwait(false);
if (prefix.Length != 0)
{
// This method calls into unsafe method which cannot run asyncly.
WritePrefix(prefix);
await WriteByteAsync(':').ConfigureAwait(false);
}
// This method calls into unsafe method which cannot run asyncly.
WriteLocalName(localName);
}