code: @Override
      public SearchFacesResult searchFaces(SearchFacesRequest request) {
          request = beforeClientExecution(request);
          return executeSearchFaces(request);
      }
docs: <p>
  For a given input face ID, searches for matching faces in the collection the face belongs to. You get a face ID
  when you add a face to the collection using the <a>IndexFaces</a> operation. The operation compares the features
  of the input face with faces in the specified collection.
  </p>
  <note>
  <p>
  You can also search faces without indexing faces by using the <code>SearchFacesByImage</code> operation.
  </p>
  </note>
  <p>
  The operation response returns an array of faces that match, ordered by similarity score with the highest
  similarity first. More specifically, it is an array of metadata for each face match that is found. Along with the
  metadata, the response also includes a <code>confidence</code> value for each face match, indicating the
  confidence that the specific face matches the input face.
  </p>
  <p>
  For an example, see Searching for a Face Using Its Face ID in the Amazon Rekognition Developer Guide.
  </p>
  <p>
  This operation requires permissions to perform the <code>rekognition:SearchFaces</code> action.
  </p>
  
  @param searchFacesRequest
  @return Result of the SearchFaces operation returned by the service.
  @throws InvalidParameterException
  Input parameter violated a constraint. Validate your parameter before calling the API operation again.
  @throws AccessDeniedException
  You are not authorized to perform the action.
  @throws InternalServerErrorException
  Amazon Rekognition experienced a service issue. Try your call again.
  @throws ThrottlingException
  Amazon Rekognition is temporarily unable to process the request. Try your call again.
  @throws ProvisionedThroughputExceededException
  The number of requests exceeded your throughput limit. If you want to increase this limit, contact Amazon
  Rekognition.
  @throws ResourceNotFoundException
  The collection specified in the request cannot be found.
  @sample AmazonRekognition.SearchFaces