class Particle:
    
    def __init__(self, name, charge, mass):
        self.name, self.charge, self.mass = name, charge, mass
        
class NuclearReaction:
    
    def __init__(self, name, reactants, products):
        self.name, self.reactants, self.products = name, reactants, products
        
    def conserves_charge(self):
        return sum([p.charge for p in self.reactants]) == sum([p.charge for p in self.products])
    
class NuclearReactor:
    
    def __init__(self, name):
        self.name = name
        self.succesful_reactions = set()
        self.available_particles = {}
    
    def add_reaction(self, reaction):
        if not reaction.conserves_charge():
            return f"{reaction.name} does not conserve charge — failed to add."
        
        for p in reaction.reactants:
                if p.name not in self.available_particles or self.available_particles[p.name] <= 0:
                    return f"Not enough {p.name} for this reaction."
                self.available_particles[p.name] -= 1
                     
        for p in reaction.products:
            self.add_particle(p)
        
        self.succesful_reactions.add(reaction.name)
    
    def add_particle(self, particle, amount=1):
        self.available_particles[particle.name] = self.available_particles.get(particle.name, 0) + amount
        
def doctester():
    """ 
    DUMMY function to run doctests.
    
    >>> p = Particle("proton", +1, 1)
    >>> n = Particle("neutron", 0, 1)
    >>> e = Particle("electron", -1, 0)
    >>> d = Particle("deuteron", +1, 2)
    
    >>> (e.name, e.charge, e.mass) == ("electron", -1, 0)
    True
    
    >>> fusion = NuclearReaction("fusion", [p, n], [d])
    >>> [r.name for r in fusion.reactants]
    ['proton', 'neutron']
    >>> [p.name for p in fusion.products]
    ['deuteron']
    
    >>> fusion.conserves_charge() # total charge of reactants and products is the same.
    True
    
    >>> bad_reaction = NuclearReaction("bad", [p, e], [d])
    >>> x = bad_reaction.conserves_charge()
    >>> print(x) # +1 -1 != +1
    False
    
    >>> reactor = NuclearReactor("Manhattan Project")
    >>> reactor.add_particle(p)
    >>> reactor.add_particle(n)
    >>> reactor.add_reaction(fusion)
    >>> reactor.add_reaction(bad_reaction)
    'bad does not conserve charge — failed to add.'
    
    
    # Add some more particles
    >>> reactor.add_particle(p, 10)  # Add 10 protons
    >>> reactor.add_particle(n, 5)  # Add 5 neutrons
    >>> reactor.add_particle(d)  # Add 1 deuteron
    
    
    >>> alpha_p = Particle("alpha", +2, 4)
    >>> nucleus_U238 = Particle("U238", +92, 238)
    >>> nucleus_U234 = Particle("U234", +90, 234)
    
    >>> alpha_decay = NuclearReaction("alpha decay", [nucleus_U238], [nucleus_U234, alpha_p])
    >>> reactor.add_reaction(alpha_decay) # We need the reactants!
    'Not enough U238 for this reaction.'
    
    >>> reactor.available_particles
    {'proton': 10, 'neutron': 5, 'deuteron': 2}
    
    >>> reactor.add_reaction(fusion)
    >>> reactor.succesful_reactions
    {'fusion'}
    """
    return "IGNORE ME"