ID,FORM,LEMMA,UPOS,XPOS,FEATS,HEAD,DEPREL,DEPS,MISC=range(10)

def read_conll(inp,max_sent=0,drop_tokens=True):
    comments=[]
    sent=[]
    yielded=0
    for line in inp:
        line=line.strip()
        if line.startswith("#"):
            comments.append(line)
        elif not line:
            if sent:
                yield sent,comments
                yielded+=1
                if max_sent>0 and yielded==max_sent:
                    break
                sent,comments=[],[]
        else:
            cols=line.split("\t")
            if drop_tokens and "-" in cols[ID]:
                continue
            sent.append(cols)
    else:
        if sent:
            yield sent,comments