diff --git a/pyinfra/server/processor/processor.py b/pyinfra/server/processor/processor.py
index 482846d..4321011 100644
--- a/pyinfra/server/processor/processor.py
+++ b/pyinfra/server/processor/processor.py
@@ -1,20 +1,19 @@
 from itertools import chain
-from typing import Union, Any
+from typing import Union, Any, Iterable, Callable
 
 from pyinfra.server.dispatcher.dispatcher import Nothing
 
 
 class OnDemandProcessor:
-    def __init__(self, processor_fn):
+    def __init__(self, fn):
+        """Function has to return an iterable and ideally is a generator."""
         self.execution_queue = chain([])
-        self.processor_fn = processor_fn
+        self.fn = fn
 
-    def submit(self, package, final) -> None:
-        """Submit computation request to execution queue; computation is performed on demand."""
-        self.execution_queue = chain(self.execution_queue, self.processor_fn(package, final=final))
+    def submit(self, package, **kwargs) -> None:
+        self.execution_queue = chain(self.execution_queue, self.fn(package, **kwargs))
 
     def compute_next(self) -> Union[Nothing, Any]:
-        """Processes the next request."""
         try:
             return next(self.execution_queue)
         except StopIteration:
diff --git a/pyinfra/server/server.py b/pyinfra/server/server.py
index b0b8df0..0111e04 100644
--- a/pyinfra/server/server.py
+++ b/pyinfra/server/server.py
@@ -23,8 +23,8 @@ def make_streamable(operation, buffer_size, batched):
 
 
 class RestOndDemandProcessor(OnDemandProcessor):
-    def __init__(self, processor_fn):
-        super(RestOndDemandProcessor, self).__init__(processor_fn=processor_fn)
+    def __init__(self, fn):
+        super(RestOndDemandProcessor, self).__init__(fn=fn)
 
     def submit(self, request, **kwargs) -> None:
         super(RestOndDemandProcessor, self).submit(request.json, final=request.method == "POST")
@@ -33,8 +33,8 @@ class RestOndDemandProcessor(OnDemandProcessor):
 class RestStreamProcessor(RestOndDemandProcessor):
     """Wraps an on-demand-processor. Combine with a webserver that provides the endpoints 'submit' and 'pickup'."""
 
-    def __init__(self, processor_fn):
-        super(RestStreamProcessor, self).__init__(processor_fn=processor_fn)
+    def __init__(self, fn):
+        super(RestStreamProcessor, self).__init__(fn=fn)
 
     def submit(self, request, **kwargs):
         super(RestStreamProcessor, self).submit(request)
diff --git a/test/unit_tests/server/processor_test.py b/test/unit_tests/server/processor_test.py
new file mode 100644
index 0000000..d19a0f2
--- /dev/null
+++ b/test/unit_tests/server/processor_test.py
@@ -0,0 +1,20 @@
+from itertools import takewhile
+
+from funcy import repeatedly
+
+from pyinfra.server.dispatcher.dispatcher import Nothing
+from pyinfra.server.processor.processor import OnDemandProcessor
+
+
+def test_processor():
+    def func(x):
+        return [x ** 2]
+
+    processor = OnDemandProcessor(func)
+
+    for i in range(10):
+        processor.submit(i)
+
+    output = list(takewhile(lambda r: r != Nothing, repeatedly(processor.compute_next)))
+
+    assert output == [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]