def describe_signature(self, signode: TextElement, mode: str, env: 'BuildEnvironment', symbol: 'Symbol') -> None:
    verify_description_mode(mode)
    signode.append(nodes.Text('{'))
    first = True
    for e in self.exprs:
        if (not first):
            signode.append(nodes.Text(', '))
        else:
            first = False
        e.describe_signature(signode, mode, env, symbol)
    if self.trailingComma:
        signode.append(nodes.Text(','))
    signode.append(nodes.Text('}'))
def describe_signature(self, signode: TextElement, mode: str, env: 'BuildEnvironment', symbol: 'Symbol') -> None:
    verify_description_mode(mode)
    signode.append(nodes.Text('{'))
    first = True
    for e in self.exprs:
        if (not first):
            signode.append(nodes.Text(', '))
        else:
            first = False
        e.describe_signature(signode, mode, env, symbol)
    if self.trailingComma:
        signode.append(nodes.Text(','))
    signode.append(nodes.Text('}'))