# Functions
GetValidPrefixes returns a string slice of the valid GitHub token prefixes.
IsValidPrefix returns if the given string is a valid ghToken prefix.
ParseGhToken builds a new ghToken struct from a GitHub token string; if token is malformed, a ghToken struct is returned that only has FullToken populated (based on the original input).
# Constants
Base62Alphabet "enum" to choose a specific base62 alphabet while encoding/decoding; more often than not, due to the alphabet that Golang's big.Int package uses, an inverted alphabet should be chosen when working with tokens produced by or intended to be consumed by GitHub.
ChecksumLength "enum" so we're not using magic numbers; after the checksum is calculated, it occupies the last 6 characters in the final GitHub token.
InputLength "enum" so we're not using magic numbers; token input is the token payload without the appended checksum.
PayloadLength "enum" so we're not using magic numbers; once the prefix and '_' are stripped from a GitHub token, the resulting payload is 36 characters long.
PrefixLength "enum" so we're not using magic numbers; prefixes of GitHub tokens are 3 characters long.
Sep is the character that separates a GitHub token's prefix from it's payload.