diff --git a/TODO b/TODO
index d1f241a9..57c25505 100644
--- a/TODO
+++ b/TODO
@@ -1,3 +1,10 @@
+- add more checks to Python vips_call()
+
+  need an exception class
+
+  how do we structure the module?
+
+
 
 
 - grep for other vips_class_find() problems: do we use it for simple class
diff --git a/python/try.py b/python/try.py
index 3e62beef..aaecc9d6 100755
--- a/python/try.py
+++ b/python/try.py
@@ -1,6 +1,5 @@
 #!/usr/bin/python
 
-import gc
 import sys
 
 # you might need this in your .bashrc
@@ -21,10 +20,10 @@ print 'a.props.width =', a.props.width
 
 print 'direct call:'
 
-a = Vips.Image.new_from_file(sys.argv[1])
+b = Vips.Image.new_from_file(sys.argv[1])
 
-print 'a.get_width() =', a.get_width()
-print 'a.props.width =', a.props.width
+print 'b.get_width() =', b.get_width()
+print 'b.props.width =', b.props.width
 
 print 'call operation:'
 
@@ -41,7 +40,7 @@ for prop in op.props:
     print '\tassigned', op.get_assigned(prop.name)
 
 op.props.left = a
-op.props.right = a
+op.props.right = b
 op2 = Vips.cache_operation_build(op)
 if op2 == None:
     print Vips.error_buffer()
@@ -54,9 +53,72 @@ print 'out.props.format =', out.props.format
 
 out.write_to_file("x.v")
 
-print 'starting shutdown ...'
-# sometimes have to do several GCs to get them all, not sure why
-#for i in range(10):
-#	gc.collect ()
-#print 'shutdown!'
+print 'generic call:'
+
+def required_input(flags):
+    enm = Vips.ArgumentFlags
+    return flags & enm.INPUT and flags & enm.REQUIRED
+
+def optional_input(flags):
+    enm = Vips.ArgumentFlags
+    return flags & enm.INPUT and not flags & enm.REQUIRED
+
+def required_output(flags):
+    enm = Vips.ArgumentFlags
+    return flags & enm.OUTPUT and flags & enm.REQUIRED
+
+def optional_output(flags):
+    enm = Vips.ArgumentFlags
+    return flags & enm.OUTPUT and not flags & enm.REQUIRED
+
+def vips_call(name, *required, **optional):
+    op = Vips.Operation.new(name)
+
+    # set required input args
+    i = 0
+    for prop in op.props:
+        flags = op.get_flags(prop.name)
+        if required_input(flags):
+            if i >= len(required):
+                print 'too few required args!'
+
+            op.props.__setattr__(prop.name, required[i])
+            i += 1
+
+    if i < len(required):
+        print 'too many required args!'
+
+    # set optional input args
+    for i in optional.keys():
+        flags = op.get_flags(i)
+        if optional_input(flags):
+            op.props.__setattr__(i, optional[i])
+
+    # call
+    op2 = Vips.cache_operation_build(op)
+    if op2 == None:
+        print Vips.error_buffer()
+
+    # gather output args 
+    out = []
+    for prop in op2.props:
+        flags = op2.get_flags(prop.name)
+        if required_output(flags):
+            out.append(op2.props.__getattribute__(prop.name))
+    for i in optional.keys():
+        flags = op2.get_flags(i)
+        if optional_output(flags):
+            out.append(op2.props.__getattribute__(i))
+
+    if len(out) == 1:
+        out = out[0]
+
+    # unref everything now we have refs to all outputs we want
+    op2.unref_outputs()
+
+    return out
+
+im = vips_call("add", a, b)
+
+im.write_to_file("x2.v")