code: def get(self, key, default=None):
          
          index = self._xxx_field_to_index.get(key)
          if index is None:
              return default
          return self._xxx_values[index]
docs: Return a value for key, with a default value if it does not exist.
  
          Args:
              key (str): The key of the column to access
              default (object):
                  The default value to use if the key does not exist. (Defaults
                  to :data:`None`.)
  
          Returns:
              object:
                  The value associated with the provided key, or a default value.
  
          Examples:
              When the key exists, the value associated with it is returned.
  
              >>> Row(('a', 'b'), {'x': 0, 'y': 1}).get('x')
              'a'
  
              The default value is :data:`None` when the key does not exist.
  
              >>> Row(('a', 'b'), {'x': 0, 'y': 1}).get('z')
              None
  
              The default value can be overrided with the ``default`` parameter.
  
              >>> Row(('a', 'b'), {'x': 0, 'y': 1}).get('z', '')
              ''
  
              >>> Row(('a', 'b'), {'x': 0, 'y': 1}).get('z', default = '')
              ''