public static string GenerateString(this Random random, int length, string prefix = "", bool includeSpaces = false)
{
var modulo = length / 3;
var builder = new StringBuilder(prefix);
for(var k = 0; k < length; k++)
{
var ch = Convert.ToChar(Convert.ToInt32(Math.Floor(26 * random.NextDouble() + 65)));
if(k % modulo != 0)
{
ch = char.ToLower(ch);
}
builder.Append(ch);
}
return builder.ToString();
}