struct SignedTransfer {
  address to;
  uint256 value;
  bytes signature;
}

function validateSignatures(SignedTransfer[] calldata transfers) external;

const scuffed = getScuffedContract(contract);
const scuffedFnCall = scuffed.validateSignatures([{
  to: wallet.address,
  value: 1000,
  signature: sign(defaultAbiCoder.encode(['address', 'bytes'], [wallet.address, 1000]))
}]);
// Modify the offset to the `transfers` array
scuffedFnCall.transfers.head.replace(0x20)
// Modify the length of the signature in the first transfer
scuffedFnCall.transfers[0].signature.length.replace(0x40)
// Modify the offset to the first transfer
scuffedFnCall.transfers[0].head.replace(0)
// Modify `value`
scuffedFnCall.transfers[0].value.replace(500)
// Encode the function calldata
const data = scuffedFnCall.encode()

type ReplaceableOffsets = {
  relative: number;   // position of the parameter relative to its parent
  absolute: number;   // absolute position of the parameter in the encoded args
  replace: (value: BigNumberish) => string; // replace the value in the encoded args
}

type DynamicOffsets = {
  head: ReplaceableOffsets;
  tail: ReplaceableOffsets;
}

{
  encode: () => string // Encode the function call with all updated parameters
  encodeArgs: () => string // Encode the input parameters without the selector
  execute: () => Promise<Transaction> // Execute the transaction with the updated parameters
  call: () => Promise<string> // Call the function with the updated parameters
  transfers: {
    length: ReplaceableOffsets
    head: ReplaceableOffsets
    tail: ReplaceableOffsets
    '0': {
      head: ReplaceableOffsets
      tail: ReplaceableOffsets

      to: ReplaceableOffsets
      value: ReplaceableOffsets

      signature: {
        length: ReplaceableOffsets
        head: ReplaceableOffsets
        tail: ReplaceableOffsets
      }
    }
  }
}