Fix converter related dill error

dilling a custom converter function causes globals to be converted
the root_state attribute on ChainStart instances includes things that can't be dilled

Author: hermansje

pythonwhat/sct_syntax.py

@@ -1,4 +1,4 @@
-from protowhat.sct_syntax import EagerChain, ExGen, LazyChainStart, state_dec_gen
+from protowhat.sct_syntax import EagerChain, ExGen, LazyChainStart, state_dec_gen, LazyChain
 from pythonwhat.checks.check_wrappers import scts
 from pythonwhat.State import State
 from pythonwhat.probe import Node, Probe, TEST_NAMES
@@ -38,6 +38,10 @@ def Ex(state=None):
     return EagerChain(state=state or State.root_state, chainable_functions=sct_dict)
 
 
+def F():
+    return LazyChain(chainable_functions=sct_dict)
+
+
 def get_chains():
     return {
         "Ex": ExGen(sct_dict, State.root_state),

pythonwhat/test_exercise.py

@@ -94,6 +94,7 @@ def prep_context():
         "from inspect import Parameter as param",
         "from pythonwhat.signatures import sig_from_params, sig_from_obj",
         "from pythonwhat.State import set_converter",
+        "from pythonwhat.sct_syntax import LazyChain as F, Ex"
     ]
     [exec(line, None, cntxt) for line in imports]
 
@@ -105,7 +106,8 @@ def prep_context():
         tree = None
 
     cntxt.update(v2_check_functions)
-    cntxt.update(get_chains())
+    # TODO: ChainStart instances cause errors when dill tries to pass manual converter functions
+    # cntxt.update(get_chains())
     return tree, cntxt