import numpy
import matplotlib.pyplot as plt

f = lambda x, y: numpy.exp(x*y)-x**2+y-1.4
xr = numpy.linspace(-2, 2, 100)
yr = numpy.linspace(-2, 2, 100)
X, Y = numpy.meshgrid(xr, yr)
Z = f(X, Y)
plt.contourf(xr, yr, Z, levels=numpy.linspace(-0.01, 0.01, 50), alpha=0.5)
plt.colorbar()
plt.show()