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import { Codec, createCodec, metadata, ScaleDecodeError } from "../common/mod.ts"
export function option<SI, SO>($some: Codec<SI, SO>): Codec<SI | undefined, SO | undefined>export function option<SI, SO, N>($some: Codec<SI, SO>, none: N): Codec<SI | N, SO | N>export function option<SI, SO, N>($some: Codec<SI, SO>, none?: N): Codec<SI | N, SO | N> {  if ($some._metadata.some((x) => x.factory === option && x.args[1] === none)) {    throw new Error("Nested option codec will not roundtrip correctly")  }  return createCodec({    _metadata: metadata("$.option", option<SI, SO, N>, $some, ...(none === undefined ? [] : [none!]) as [N]),    _staticSize: 1 + $some._staticSize,    _encode(buffer, value) {      if ((buffer.array[buffer.index++] = +(value !== none))) {        $some._encode(buffer, value as SI)      }    },    _decode(buffer) {      switch (buffer.array[buffer.index++]) {        case 0:          return none as N        case 1: {          const value = $some._decode(buffer)          if (value === none) {            throw new ScaleDecodeError(this, buffer, "Some(None) will not roundtrip correctly")          }          return value        }        default:          throw new ScaleDecodeError(this, buffer, "Option discriminant neither 0 nor 1")      }    },    _assert(assert) {      if (assert.value === none) return      $some._assert(assert)    },  })}