public double?ExtractCourseFromHtml(string html_document_2)
{
if (html_document_2.Contains("Error - VesselFinder"))
{
return(null);
}
string node = _creator.CreatePrepareAndVerifyRowNodeString(html_document_2);
string course = _stringParser.GetTrimmedCourse(node);
return(_stringParser.ParsedTrimmedNullableDouble(course));
}