parameters: (self)
return_statement: return self.left_on[-1]
docstring: This is our asof key, the 'on'
docstring_summary: This is our asof key, the 'on'
docstring_tokens: This is our asof key the on
function: def _asof_key(self):
          """ This is our asof key, the 'on' """
          return self.left_on[-1]
function_tokens: def _asof_key ( self ) : return self . left_on [ - 1 ]