private string calculateDescription()
{
ISpan previous = null;
return(Spans
.Aggregate(
new StringBuilder(),
(builder, span) =>
{
builder.Append(chooseSeparator(previous, span));
builder.Append(toString(span));
previous = span;
return builder;
})
.ToString()
.Trim());
string toString(ISpan span)
=> span is TextSpan text?text.Text.Trim() : string.Empty;
string chooseSeparator(ISpan first, ISpan second)
=> first is TextSpan && second is TextSpan ? "" : " ";
}