A sequence is a collection where the elements are ordered. An element may be part of a sequence more than once. Sequence is itself an instance of the metatype SequenceType. A Sentence is not a subtype of Bag. The common supertype of Sentence and Bags is Collection.

conformsTo
`Collection(T)`

**Operations**

`=(object2 : OclSelf) : Boolean`

precedence:
`EQUALITY`

True if
`self`

contains the same elements as s in the same order.

`<>(object2 : OclSelf) : Boolean`

precedence:
`EQUALITY`

`append(object : T[?]) : Sequence(T)`

The sequence of elements, consisting of all elements of
`self`

, followed by object.

`at(index : Integer) : T[?] invalidating`

The i-th element of sequence.

`excluding(object : OclAny[?]) : Sequence(T)`

The sequence containing all elements of
`self`

apart from all occurrences of object.

The order of the remaining elements is not changed.

`first() : T[?] invalidating`

The first element in
`self`

.

`flatten(T2)() : Sequence(T2)`

Redefines the Collection operation. If the element type is not a collection type, this results in the same sequence as
`self`

.
If the element type is a collection type, the result is the sequence containing all the elements
of all the recursively flattened elements of
`self`

. The order of the elements is partial.

`including(object : T[?]) : Sequence(T)`

The sequence containing all elements of
`self`

plus object added as the last element.

`indexOf(obj : OclAny[?]) : Integer`

The index of object obj in the ordered collection.

`insertAt(index : Integer, object : T[?]) : Sequence(T) invalidating`

The sequence consisting of
`self`

with object inserted at position index.

`last() : T[?] invalidating`

The last element in
`self`

.

`prepend(object : T[?]) : Sequence(T)`

The sequence consisting of object, followed by all elements in
`self`

.

`reverse() : Sequence(T)`

The sequence containing the same elements but with the opposite order.

`selectByKind(TT)(type : Metaclass(TT)) : Sequence(TT)`

`selectByType(TT)(type : Metaclass(TT)) : Sequence(TT)`

`subSequence(lower : Integer, upper : Integer) : Sequence(T) invalidating`

The sub-sequence of
`self`

starting at number lower, up to and including element number upper.

**Iterations**

`closure(i : T | lambda : Lambda T() : OrderedSet(T)) : OrderedSet(T)`

The closure of applying body transitively to every distinct element of the source collection.

`collect(V)(i : T[?] | lambda : Lambda T() : V[?]) : Sequence(V)`

`collectNested(V)(i : T[?] | lambda : Lambda T() : V[?]) : Sequence(T)`

The sequence of elements that results from applying body to every member of the source ordered collection.

`reject(i : T[?] | lambda : Lambda T() : Boolean) : Sequence(T)`

The subsequence of the source sequence for which body is
`false`

.

`select(i : T[?] | lambda : Lambda T() : Boolean) : Sequence(T)`

The subsequence of the source sequence for which body is
`true`

.

`sortedBy(i : T[?] | lambda : Lambda T() : OclAny) : Sequence(T)`

Results in the Sequence containing all elements of the source collection. The element for which body has the lowest value comes first, and so on. The type of the body expression must have the < operation defined. The < operation must return a Boolean value and must be transitive (i.e., if a < b and b < c then a < c).