code: func NewMCS(channelPolicyManagerGetter policies.ChannelPolicyManagerGetter, localSigner crypto.LocalSigner, deserializer mgmt.DeserializersManager) *MSPMessageCryptoService {
  	return &MSPMessageCryptoService{channelPolicyManagerGetter: channelPolicyManagerGetter, localSigner: localSigner, deserializer: deserializer}
  }
docs: // NewMCS creates a new instance of MSPMessageCryptoService
  // that implements MessageCryptoService.
  // The method takes in input:
  // 1. a policies.ChannelPolicyManagerGetter that gives access to the policy manager of a given channel via the Manager method.
  // 2. an instance of crypto.LocalSigner
  // 3. an identity deserializer manager