code: def compiled_foreign_keys(self):
          
  
          def get_column_args(column):
              tmp = []
              for arg_name, arg_val in column.items():
                  if arg_name not in ('name', 'type', 'reference'):
                      if arg_name in ('server_default', 'server_onupdate'):
                          arg_val = '"{}"'.format(arg_val)
                      tmp.append(ALCHEMY_TEMPLATES.column_arg.safe_substitute(arg_name=arg_name,
                                                                              arg_val=arg_val))
              return ", ".join(tmp)
  
          def get_fkey_args(column):
              table = column['reference']['table']
              column = column['reference']['column']
              return ALCHEMY_TEMPLATES.foreign_key_arg.safe_substitute(reference_table=table, reference_column=column)
  
          res = []
          for column in self.foreign_key_definitions:
              column_args = get_column_args(column)
              column_type, type_params = ModelCompiler.get_col_type_info(column.get('type'))
              column_name = column.get('name')
              reference = get_fkey_args(column)
              if column_type in MUTABLE_DICT_TYPES:
                  column_type = ALCHEMY_TEMPLATES.mutable_dict_type.safe_substitute(type=column_type,
                                                                                    type_params=type_params)
                  type_params = ''
              res.append(
                  ALCHEMY_TEMPLATES.foreign_key.safe_substitute(column_name=column_name,
                                                                column_type=column_type,
                                                                column_args=column_args,
                                                                foreign_key_args=reference,
                                                                type_params=type_params))
          join_string = "\n" + self.tab
          return join_string.join(res)
docs: Returns compiled foreign key definitions