def _make_expr_ops(self, op_list, op_dict=None, op_class=None):
for o in op_list:<EOL><INDENT>if op_dict is not None:<EOL><INDENT>if o in op_dict:<EOL><INDENT>self._op_expr[o] = op_dict[o]<EOL><DEDENT>else:<EOL><INDENT>l.warning("<STR_LIT>", o)<EOL><DEDENT><DEDENT>else:<EOL><INDENT>if hasattr(op_class, o):<EOL><INDENT>self._op_expr[o] = getattr(op_class, o)<EOL><DEDENT>else:<EOL><INDENT>l.warning("<STR_LIT>", o, op_class)<EOL><DEDENT><DEDENT><DEDENT>
Fill up `self._op_expr` dict.

:param op_list:     A list of operation names.
:param op_dict:     A dictionary of operation methods.
:param op_class:    Where the operation method comes from.
:return: