fix(test) functor repr now prints @ instead of chain

Phys/FunTuple/tests/test_FunctorCollection.py

@@ -68,7 +68,7 @@ def test_repr_loki():
 
 
 def test_str(simple_fc):
-    _str = """    PT: ('chain( ::Functors::Common::Rho_Coordinate{}, ::Functors::Track::ThreeMomentum{} )', ['Functors/Common.h', 'Functors/TrackLike.h'], '( RHO_COORDINATE chain THREEMOMENTUM )')
+    _str = """    PT: ('Functors::chain( ::Functors::Common::Rho_Coordinate{}, ::Functors::Track::ThreeMomentum{} )', ['Functors/Common.h', 'Functors/TrackLike.h'], '( RHO_COORDINATE @ THREEMOMENTUM )')
     X: X
     Y: Y"""
     assert _str in str(simple_fc)