Returns the only element of a sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence.
An Iterable to return a single element from.
Optional
A function to test an element for a condition.
The single element of the input sequence that satisfies a condition.
TSource The type of the elements of source.
Returns the only element of a sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence.