code: def get_phi_variables(self, block_addr):
          
  
          if block_addr not in self._phi_variables_by_block:
              return dict()
          variables = { }
          for phi in self._phi_variables_by_block[block_addr]:
              variables[phi] = self._phi_variables[phi]
          return variables
docs: Get a dict of phi variables and their corresponding variables.
  
          :param int block_addr:  Address of the block.
          :return:                A dict of phi variables of an empty dict if there are no phi variables at the block.
          :rtype:                 dict