Wordcloud Python with generate_from_frequencies

I'm trying to create a wordcloud from csv file. The csv file, as an example, has the following structure:

a,1
b,2
c,4
j,20

It has more rows, more or less 1800. The first column has string values (names) and the second column has their respective frequency (int). Then, the file is read and the key,value row is stored in a dictionary (d) because later on we will use this to plot the wordcloud:

reader = csv.reader(open('namesDFtoCSV', 'r',newline='\n'))
d = {}
for k,v in reader:
    d[k] = v

Once we have the dictionary full of values, I try to plot the wordcloud:

#Generating wordcloud. Relative scaling value is to adjust the importance of a frequency word.
#See documentation: https://github.com/amueller/word_cloud/blob/master/wordcloud/wordcloud.py
    wordcloud = WordCloud(width=900,height=500, max_words=1628,relative_scaling=1,normalize_plurals=False).generate_from_frequencies(d)
    plt.imshow(wordcloud, interpolation='bilinear')
    plt.axis("off")
    plt.show()
But an error is thrown:

    Traceback (most recent call last):
    File ".........../script.py", line 19, in <module>
    wordcloud = WordCloud(width=900,height=500, max_words=1628,relative_scaling=1,normalize_plurals=False).generate_from_frequencies(d)
    File "/usr/local/lib/python3.5/dist-packages/wordcloud/wordcloud.py", line  360, in generate_from_frequencies
    for word, freq in frequencies]
    File "/usr/local/lib/python3.5/dist-packages/wordcloud/wordcloud.py", line 360, in <listcomp>
    for word, freq in frequencies]
    TypeError: unsupported operand type(s) for /: 'str' and 'float

Finally, the documentation says:

def generate_from_frequencies(self, frequencies, max_font_size=None):
    """Create a word_cloud from words and frequencies.
    Parameters
    ----------
    frequencies : dict from string to float
        A contains words and associated frequency.
    max_font_size : int
        Use this font-size instead of self.max_font_size
    Returns
    -------
    self
```python

So, I don't understand why is trowing me this error if I met the requirements of the function. I hope someone can help me, thanks.

**Note**

I work with worldcloud 1.3.1