private async Task <bool> VerifyInstruction(Instruction instruction, ICollection <Transaction> siblings) { if (siblings.Any(x => x.Instructions.Any(y => y.InstructionId.SequenceEqual(instruction.InstructionId)))) { return(false); } if (!_signatureService.VerifyInstruction(instruction)) { return(false); } return(!await _instructionRepository.HaveInstruction(instruction.InstructionId)); }