Define constructor request and usecase.

cml/shared/request.py

@@ -24,3 +24,9 @@ class KnowledgeSearchRequest:
     reconstructor: Reconstructor
     data_source: DataSource
     deconstruction_settings: DeconstructionSettings
+
+
+@dataclass
+class CreateConstructorRequest:
+    settings: ConstructionSettings
+    ml_models: Iterable

cml/usecases/query.py

 from cml.usecases.usecase import Usecase
-from cml.domain import Preprocessor, DataSource, LearnblockIdentifier
+from cml.domain import (
+    Preprocessor,
+    DataSource,
+    LearnblockIdentifier,
+    Constructor
+)
 
 
 class PreprocessUsecase(Usecase):
@@ -13,6 +18,11 @@ class PreprocessUsecase(Usecase):
         return data_source
 
 
+class CreateConstructorUsecase(Usecase):
+    def process(self, request):
+        return Constructor(request.ml_models, request.settings)
+
+
 class KnowledgeSearchUsecase(Usecase):
     def process(self, request):
         pass