null_entry

/**
 * This functions is an alias for creating string entry from null.
 * The main difference between using this function an simply str_entry with second argument null
 * is that this function will also keep a note in the metadata that type might not be final.
 * For example when we need to guess column type from rows because schema was not provided,
 * and given column in the first row is null, it might still change once we get to the second row.
 * That metadata is used to determine if string_entry was created from null or not.
 *
 * By design flow assumes when guessing column type that null would be a string (the most flexible type).
 *
 * @return Entry<?string>
 */
null_entry(string $name, ?Metadata $metadata) : Entry