{#- Given a method parameter, returns a FuzzIL `Parameter`, with nullable
    parameters represented via the `.either` case. -#}
{%- macro to_fuzzilli_parameter(parameter) -%}
    {%- if parameter.kind.is_nullable -%}
    .either(.{{parameter.kind|format_il_type}}, .undefined),
    {%- else -%}
    .plain(.{{parameter.kind|format_il_type}}),
    {%- endif -%}
{%- endmacro -%}