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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def contourf(f, vertexlabels=None, **kwargs):
    '''Filled contour plot on a 2D triangle of a function evaluated at
    barycentric 2-simplex points.

    Function signature is identical to :func:`contour` with the caveat that
    ``**kwargs`` are passed on to :func:`plt.tricontourf`.'''
    return _contour(f, vertexlabels, contourfunc=plt.tricontourf, **kwargs)