Add more documentation about input/output semantic type params to the is_fairstep decorator

Author: raar1

fairworkflows/fairstep.py

@@ -390,7 +390,17 @@ def is_fairstep(label: str = None, is_pplan_step: bool = True, is_manual_task: b
         is_script_task (str): Denotes whether this step is a bpmn.ScriptTask
 
     All additional arguments are expected to correspond to input parameters of the decorated
-    function, and are used to provide extra semantic types for that parameter.
+    function, and are used to provide extra semantic types for that parameter. For example,
+    consider the following decorated function:
+        @is_fairstep(label='Addition', a='http://www.example.org/number', out1='http://www.example.org/float')
+        def add(a:float, b:float) -> float:
+            return a + b
+    1. Note that using 'a' as parameter to the decorator allows the user to provide a URI for a semantic type
+    that should be associated with the function's input parameter, 'a'. This can be either a string, an
+    rdflib.URIRef, or a list of these.
+    2. Note that the return parameter is referred to using 'out1', because it does not otherwise have a name.
+    In this case, the function only returns one value. However, if e.g. a tuple of 3 values were returned,
+    you could use out1, out2 and out3 to set the semantic types of each return value, if so desired.
     """
 
     def _modify_function(func):