# src/runtimeTypes.ts

    import * as t from 'io-ts'

    export const HexString = t.refinement(
        t.string,
        v =>
            v.slice(0, 2) === '0x' &&
            v.slice(2).replace(/[0-9a-fA-F]*/, '').length === 0 &&
            v.length % 2 === 0,
        'HexString'
    )

    export const Bytes32 = t.refinement(
        HexString,
        v => v.length === 32 * 2 + 2,
        'Bytes32'
    )
    export const Bytes64 = t.refinement(
        HexString,
        v => v.length === 64 * 2 + 2,
        'Bytes64'
    )