input: Write a python function to predict the growth rate of a particular crop in a given environment using the GrowthRatePredictor class.
  assert GrowthRatePredictor("corn", "tropical").predict_growth_rate() == expected_growth_rate_for_corn_in_tropical
  assert GrowthRatePredictor("wheat", "temperate").predict_growth_rate() == expected_growth_rate_for_wheat_in_temperate
  assert GrowthRatePredictor("rice", "subtropical").predict_growth_rate() == expected_growth_rate_for_rice_in_subtropical
output: class GrowthRatePredictor:
      def __init__(self, crop, environment):
          self.crop = crop
          self.environment = environment
      
      def predict_growth_rate(self):
          growth_rates = {
              "corn": {
                  "tropical": 1.2,
                  "temperate": 0.8,
                  "subtropical": 1.0
              },
              "wheat": {
                  "tropical": 0.6,
                  "temperate": 1.1,
                  "subtropical": 0.9
              },
              "rice": {
                  "tropical": 1.3,
                  "temperate": 0.7,
                  "subtropical": 1.1
              }
          }
          return growth_rates.get(self.crop, {}).get(self.environment, 0)