word_cloud: Missing parameter contour_width in 1.4.1 (but used in the examples)

Description

I installed from pypi (pip install wordcloud) which results in a version 1.4.1 (as of March 28 2018)

If I run the mask example I get an error: TypeError: __init__() got an unexpected keyword argument 'contour_width'

Steps/Code to Reproduce

Just install from pypi (1.4.1) and run the masked.py example from

Also see line contour_width 29/30 in examples/masked.py source:

wc = WordCloud(background_color="white", max_words=2000, mask=alice_mask,
stopwords=stopwords, contour_width=3, contour_color='steelblue')

And compare the WordCloud __init__ from 1.4.1 where there seems to be no parameter contour_width defined

def __init__(self, font_path=None, width=400, height=200, margin=2,
                 ranks_only=None, prefer_horizontal=.9, mask=None, scale=1,
                 color_func=None, max_words=200, min_font_size=4,
                 stopwords=None, random_state=None, background_color='black',
                 max_font_size=None, font_step=1, mode="RGB",
                 relative_scaling=.5, regexp=None, collocations=True,
                 colormap=None, normalize_plurals=True):

Expected Results

Probably change / adapt the example or add the parameter with a default to 1.4.1

Actual Results

TypeError: __init__() got an unexpected keyword argument 'contour_width'

Versions

Windows-7-6.1.7601-SP1 Python 3.6.3 |Anaconda, Inc.| (default, Oct 15 2017, 03:27:45) [MSC v.1900 64 bit (AMD64)] NumPy 1.14.2 matplotlib 2.2.2 wordcoud 1.4.1