keras训练出现_got multiple values for argument 'units'

import pandas as pd
import numpy as np
import jieba
import jieba.posseg as pseg
import re
#import csv
import string
#from keras import models
from keras import layers
from keras.utils.np_utils import to_categorical
from keras.preprocessing.text import Tokenizer
from sklearn.preprocessing import LabelEncoder
#from sklearn.feature_extraction.text import CountVectorizer
from gensim.models import word2vec
from keras.preprocessing.sequence import pad_sequences
from keras.layers import *
#from keras.models import Model
#from sklearn import metrics
from keras.models import load_model
from keras.models import Sequential

main_input = Input(shape=(maxLen,), dtype='float64')
# 词嵌入（使用预训练word2vec的词向量，自定义权重矩阵，100是输出的词向量维度）
embedder = Embedding(len(vocab) + 1, 100, input_length=maxLen, weights=[embedding_matrix], trainable=False)
model=Sequential()
model.add(embedder)
model.add(Conv1D(256,3,padding='same',activation='relu'))
model.add(MaxPool1D(maxLen-5,3,padding='same'))
model.add(Conv1D(32,3,padding='same',activation='relu'))
model.add(Flatten())
model.add(Dropout(0.3))
model.add(Dense(256,activation='relu'))
model.add(Dropout(0.2))
model.add(Dense(5,units=2, activation='softmax'))
model.compile(loss='categorical_crossentropy', optimizer='adam', metrics=['accuracy'])
history=model.fit(trainSeq, trainCate, batch_size=256, epochs=6,validation_split=0.2)
model.save("TextCNN")

训练的时候出现错误：TypeError: __init__() got multiple values for argument 'units'

34行，dense()的默认参数第一个就是unit，你已经赋值一个5了，第二个参数又是unit=2，变成重新赋值了。