text: import ee
  from ee_plugin import Map
  
  # This function gets NDVI from Landsat 5 imagery.
  
  
  def getNDVI(image):
      return image.normalizedDifference(['B4', 'B3'])
  
  
  # Load two Landsat 5 images, 20 years apart.
  image1 = ee.Image('LANDSAT/LT05/C01/T1_TOA/LT05_044034_19900604')
  image2 = ee.Image('LANDSAT/LT05/C01/T1_TOA/LT05_044034_20100611')
  
  # Compute NDVI from the scenes.
  ndvi1 = getNDVI(image1)
  ndvi2 = getNDVI(image2)
  
  # Compute the difference in NDVI.
  ndviDifference = ndvi2.subtract(ndvi1)
  # Load the land mask from the SRTM DEM.
  landMask = ee.Image('CGIAR/SRTM90_V4').mask()
  
  # Update the NDVI difference mask with the land mask.
  maskedDifference = ndviDifference.updateMask(landMask)
  
  # Display the masked result.
  vizParams = {'min': -0.5, 'max': 0.5,
               'palette': ['FF0000', 'FFFFFF', '0000FF']}
  Map.setCenter(-122.2531, 37.6295, 9)
  Map.addLayer(maskedDifference, vizParams, 'NDVI difference')
  