FilterDocumentation.swift

/// Returns an array containing, in order, the elements of the sequence
/// that satisfy the given predicate.
/// - Parameter shouldInclude: A closure that takes an element of the
///   sequence as its argument and returns a Boolean value indicating
///   whether the element should be included in the returned array.
/// - Returns: An array of the elements that `includeElement` allowed.
public func filter(_ isIncluded: (Element) throws -> Bool) rethrows -> [Element]