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# ?E in ?Sterm

E belongs to the set term Sterm.
*?E*
- A Prolog term.
*?Sterm*
- A set term.

## Description

This constraint states that E belongs to the set term Sterm. If E is
not a known value the constraint is delayed. It is activated as soon as
E becomes a known value. If Sterm is a ground set and E is known it
checks if E belongs to Sterm.

### Fail Conditions

Fails if E cannot belong to Sterm.
### Resatisfiable

No.
## Examples

[eclipse 4]: S `:: {}.. {1,2,3}, E in S.
E = E
S = S{{} .. {1, 2, 3}}
Delayed goals:
E in_s S{{} .. {1, 2, 3}}
yes.
[eclipse 5]: S `:: {}.. {1,2,3}, 1 in S.
S = S{{1} .. {1, 2, 3}}
yes.

## See Also

`:: / 2, notin / 2