import numpy
from matplotlib import pyplot
x=numpy.linspace(-3,3,50)
y=2*x+1
pyplot.figure(num=1,figsize=(5,5))
pyplot.plot(x,y,linewidth=10,zorder=1)
ax=pyplot.gca()
ax.spines['right'].set_color('none')
ax.spines['top'].set_color('none')
ax.xaxis.set_ticks_position('bottom')
ax.spines['bottom'].set_position(('data',0))
ax.yaxis.set_ticks_position('left')
ax.spines['left'].set_position(('data',0))
for label in ax.get_xticklabels()+ax.get_yticklabels():
label.set_fontsize(12)
label.set_bbox(dict(facecolor='white', edgecolor='none', alpha=0.7))
pyplot.show()