Sequence provides a unified api for access to sequential data types, like Strings, Arrays, Files, IOs, and Enumerations. Each sequence encapsulates some data and a current position within it. Some operations apply to data at (or relative to) the position, others are independant of position. The api contains operations for moving the position, reading and writing data (with or without moving the position) forward or backward from the current position or anywhere, scanning for patterns (like StringScanner, but it works in Files too, among others), and saving a position that will remain valid even after data is deleted or inserted elsewhere within the sequence. There are also some utility classes for making sequences reversed or circular, turning one-way sequences into two-way, buffering, and making sequences that are subsets or aggregations of existing sequences.