# Functions
GenerateLoginToken generates a short term login token to be used as token authentication ("m.login.token").
GetUserFromToken returns the user associated with the token Returns the error if something goes wrong.
ValidateToken validates that the token is parseable and signed by this server.
# Constants
Gen is a common caveat for every token.
TimePrefix is a common prefix for every expiry caveat.
UserPrefix is a common prefix for every user_id caveat.
# Structs
TokenOptions represent parameters of Token.