func Any[T any](seq iter.Seq[T], pred func(T) bool) bool
Any reports whether any pred(t) for t in seq returns true.
func Contains[T comparable](seq iter.Seq[T], x T) bool
Contains reports whether x is an element of the sequence seq.
func Every[T any](seq iter.Seq[T], pred func(T) bool) bool
Every reports whether every pred(t) for t in seq returns true, stopping at the first false element.
func First[T any](seq iter.Seq[T]) (z T, ok bool)
First returns the first value of seq and true. If seq is empty, it returns the zero value of T and false.
func Len[T any](seq iter.Seq[T]) (n int)
Len returns the number of elements in the sequence (by iterating).