code: def find_unique_values(input_file, property_name):
      '''
      Find unique values of a given property in a geojson file.
  
      Args
          input_file (str): File name.
          property_name (str): Property name.
      Returns
          List of distinct values of property. If property does not exist, it returns None.
      '''
  
      with open(input_file) as f:
          feature_collection = geojson.load(f)
  
      features = feature_collection['features']
      values = np.array([feat['properties'].get(property_name)
                         for feat in features])
      return np.unique(valuesf find_unique_values(input_file, property_name):
      '''
      Find unique values of a given property in a geojson file.
  
      Args
          input_file (str): File name.
          property_name (str): Property name.
      Returns
          List of distinct values of property. If property does not exist, it returns None.
      '''
  
      with open(input_file) as f:
          feature_collection = geojson.load(f)
  
      features = feature_collection['features']
      values = np.array([feat['properties'].get(property_name)
                         for feat in features])
      return np.unique(values)
docs: Find unique values of a given property in a geojson file.
  
      Args
          input_file (str): File name.
          property_name (str): Property name.
      Returns
          List of distinct values of property. If property does not exist, it returns None.