function getDynamoSpec(shim, original, name, args) {
  const [{ input }] = args
  return new OperationSpec({
    name: this.commandName,
    parameters: setDynamoParameters(this.endpoint, input),
    callback: shim.LAST,
    opaque: true,
    promise: true
  })
}
Returns the spec for Dynamo commands

@param {Shim} shim
@param {original} original Original middleware function
@param {String} name Name of the calling function
@param {Array} args Arguments for the middleware function
@returns {Object}