def melt_vocab_dic(vocab1, vocab2):
    """Melts vocab dictionnary by adding the counts of each words.
    Vocab dictionnaries must be s.t.:
    vocab = {'word' : count_occurencies_word}
    Args:
        vocab1 : dic
        vocab2 : dic
    Returns:
        vocab : dic
    """
    for word in vocab2:
        if word in vocab1:
            vocab1[word] = vocab1[word] + vocab2[word]
        else:
            vocab1[word] = vocab2[word]
    return vocab1