String to Dict conversion

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1

Hi I need a help . My Macro looks like this
{% macro test_macro(source_name, table_name) -%}

{% set columns_string = get_column_names_from_source(source_name, table_name) %}
{% set columns_list = fromjson(columns_string | tojson) %}


{% set re = modules.re %}

{%- for col in columns_list.values() %}
    do something 
{%- endfor %}

{%- endmacro %}
I can see columns_list=fromjson(columns_string | tojson) is working and it’s a dict. but when i do {%- for col in columns_list.values() %} it errors out
‘str object’ has no attribute ‘values’. not able to solve this