# RegexPattern.Options.isStrictSubset(of:)

- **Module:** RegexPattern.Options
- **Package:** libtmux-swift
- **Language:** Swift
- **Kind:** method
- **Page:** https://libtmux.org/reference/swift/regexpattern-options-isstrictsubset(of-)/

```
RegexPattern.Options.isStrictSubset(of:)(of: Self) -> Bool
```

Returns a Boolean value that indicates whether this set is a strict subset of the given set.

Set *A* is a strict subset of another set *B* if every member of *A* is
also a member of *B* and *B* contains at least one element that is not a
member of *A*.

    let employees: Set = ["Alicia", "Bethany", "Chris", "Diana", "Eric"]
    let attendees: Set = ["Alicia", "Bethany", "Diana"]
    print(attendees.isStrictSubset(of: employees))
    // Prints "true"

    // A set is never a strict subset of itself:
    print(attendees.isStrictSubset(of: attendees))
    // Prints "false"

- Parameter other: A set of the same type as the current set.
- Returns: `true` if the set is a strict subset of `other`; otherwise,
  `false`.