fails:Hash#delete_if yields two arguments: key and value
fails:Hash#delete_if removes every entry for which block is true and returns self
fails:Hash#delete_if processes entries with the same order as each()
fails:Hash#delete_if raises a RuntimeError if called on a frozen instance
fails:Hash#delete_if returns an Enumerator if called on a non-empty hash without a block
fails:Hash#delete_if returns an Enumerator if called on an empty hash without a block
fails:Hash#delete_if returns an Enumerator if called on a frozen instance
