# Functions
NewEncoding returns a new Encoding defined by the given alphabet, which must be a 91-byte string that does not contain CR or LF ('\r', '\n').
# Variables
StdEncoding is the standard base91 encoding (that is, the one specified at http://base91.sourceforge.net).
# Structs
An Encoding is a base 91 encoding/decoding scheme defined by a 91-character alphabet.
# Type aliases
A CorruptInputError is returned if invalid base91 data is encountered during decoding.