{{- bos_token }}
{%- if messages[0]['role'] == 'system' -%}
    {%- if messages[1] is not defined or messages[1]['role'] != 'user' -%}
        {{- raise_exception("System message must be followed by a user message") }}
    {%- endif -%}
    {%- set system_content = messages[0]['content'] -%}
    {%- set loop_messages = messages[1:] -%}
    {%- set first_user_has_system = true -%}
{%- else -%}
    {%- set system_content = "" -%}
    {%- set loop_messages = messages -%}
    {%- set first_user_has_system = false -%}
{%- endif -%}
{%- for message in loop_messages -%}
    {%- if (message['role'] == 'user') != (loop.index0 % 2 == 0) -%}
        {{- raise_exception("Conversation roles must alternate user/assistant/user/assistant/...") }}
    {%- endif -%}
    {%- if message['role'] == 'user' -%}
        {{- '<|user_start|>' }}
        {%- if loop.first and first_user_has_system -%}
            {{- system_content + '\n\n' }}
        {%- endif -%}
        {%- if message['content'] is not string -%}
            {{- raise_exception("User messages must contain string content") }}
        {%- endif -%}
        {{- message['content'] }}
        {{- '<|user_end|>' }}
    {%- elif message['role'] == 'assistant' -%}
        {{- '<|assistant_start|>' }}
        {%- if message['content'] is string -%}
            {{- message['content'] }}
        {%- elif message['content'] is iterable -%}
            {%- for part in message['content'] -%}
                {%- if part['type'] == 'text' -%}
                    {{- part.get('text', '') }}
                {%- elif part['type'] == 'python' -%}
                    {{- '<|python_start|>' + part.get('text', '') + '<|python_end|>' }}
                {%- elif part['type'] == 'python_output' -%}
                    {{- '<|output_start|>' + part.get('text', '') + '<|output_end|>' }}
                {%- else -%}
                    {{- raise_exception("Unknown assistant content part: " + part['type']) }}
                {%- endif -%}
            {%- endfor -%}
        {%- else -%}
            {{- raise_exception("Unsupported assistant content type") }}
        {%- endif -%}
        {{- '<|assistant_end|>' }}
    {%- endif -%}
{%- endfor -%}
{%- if add_generation_prompt -%}
    {{- '<|assistant_start|>' }}
{%- endif -%}