Function isCastle960

isCastle960(value): value is
    | "bb"
    | "wb"
    | "bd"
    | "ba"
    | "bg"
    | "bc"
    | "be"
    | "bf"
    | "bh"
    | "wd"
    | "wa"
    | "wg"
    | "wc"
    | "we"
    | "wf"
    | "wh"
Whether the given value represents a valid Castle960 or not.
Parameters
- value: unknown
Returns value is
    | "bb"
    | "wb"
    | "bd"
    | "ba"
    | "bg"
    | "bc"
    | "be"
    | "bf"
    | "bh"
    | "wd"
    | "wa"
    | "wg"
    | "wc"
    | "we"
    | "wf"
    | "wh"