In [97]: from net.imglib2.outofbounds import OutOfBoundsFactory

In [98]: c = env.op("filter.gauss").inType(Img, Double.TYPE, OutOfBoundsFactory).outType(Img).computer()

In [99]: c
Out[99]: <java object 'org.scijava.ops.engine.matcher.impl.OpWrappers$Computer3OpWrapper$1GenericTypedComputer3'>

In [100]: c.infoTree().toString()
Out[100]: 'org.scijava.ops.image.filter.gauss.Gaussians.gaussRAISingleSigma(net.imglib2.RandomAccessibleInterval<I>,double,net.imglib2.outofbounds.OutOfBoundsFactory<I, net.imglib2.RandomAccessibleInterval<I>>,net.imglib2.RandomAccessibleInterval<O>)'

In [101]: sig = Ops.signature(c)

In [102]: sig
Out[102]: '|Info:org.scijava.ops.image.filter.gauss.Gaussians.gaussRAISingleSigma(net.imglib2.RandomAccessibleInterval<I>,double,net.imglib2.outofbounds.OutOfBoundsFactory<I, net.imglib2.RandomAccessibleInterval<I>>,net.imglib2.RandomAccessibleInterval<O>)@0-SNAPSHOT{}'

In [104]: try:
     ...:     o = env.opFromSignature(sig, Nil.of(Computers.Arity3))
     ...: except Exception as e:
     ...:     from scyjava import jstacktrace
     ...:     print(jstacktrace(e))
     ...:
java.lang.IllegalArgumentException: TODO
	at org.scijava.ops.engine.impl.DefaultOpEnvironment.opFromInfoChain(DefaultOpEnvironment.java:225)
	at org.scijava.ops.api.OpEnvironment.opFromInfoChain(OpEnvironment.java:165)
	at org.scijava.ops.api.OpEnvironment.opFromSignature(OpEnvironment.java:182)