Throws exception when Predicate is not called

[mikulatomas]

In [1]: from lnn import Predicate, And
   ...: 
   ...: P = Predicate("P", arity=0)
   ...: 

In [2]: And(P(), P())
Out[2]: <lnn.symbolic.logic.And at 0x1107e4d30>

In [3]: And(P(), P)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
Input In [3], in <module>
----> 1 And(P(), P)

File ~/Gits/LNN/lnn/symbolic/logic.py:1110, in _NAryNeuron.__init__(self, *formula, **kwds)
   1109 def __init__(self, *formula, **kwds):
-> 1110     super().__init__(*formula, arity=len(formula), **kwds)

File ~/Gits/LNN/lnn/symbolic/logic.py:976, in _ConnectiveNeuron.__init__(self, *formula, **kwds)
    975 def __init__(self, *formula, **kwds):
--> 976     super().__init__(*formula, **kwds)
    977     self.neuron = _NeuralActivation(kwds.get("neuron", {}).get("type"))(
    978         self.propositional, self.arity, self.world, **kwds.get("neuron", {})
    979     )
    980     self.func = self.neuron.function(
    981         self.__class__.__name__, direction=Direction.UPWARD
    982     )

File ~/Gits/LNN/lnn/symbolic/logic.py:971, in _ConnectiveFormula.__init__(self, *formula, **kwds)
    970 def __init__(self, *formula: _Formula, **kwds):
--> 971     super().__init__(*formula, **kwds)

File ~/Gits/LNN/lnn/symbolic/logic.py:156, in _Formula.__init__(self, name, arity, world, *formula, **kwds)
    154     for subformula in formula:
    155         if isinstance(subformula, Predicate):
--> 156             raise ValueError(
    157                 f"predicate {subformula} inside formula must be called"
    158             )
    160 # formula naming
    161 self.name = (
    162     name
    163     if name
    164     else (f"{self.class_name}_{_Formula.unique_num[self.class_name]}")
    165 )

ValueError: predicate P inside formula must be called

[NaweedAghmad]

Can we resubmit this so that travis doesn't trigger?

[mikulatomas]

Can we resubmit this so that travis doesn't trigger?

Done :)

[NaweedAghmad]

perhaps we could wrap it similar to the content in https://github.com/IBM/LNN/blob/master/lnn/_exceptions.py?