How to use key-value pairs in data files

For a data.yml like

key1: value1
key2: value2

How should I get a list of keys/values in a forloop? I tried

{%- for datum in -%}
{{ datum }}
{%- endfor -%}

and I got key1value1key2value2.... How to separate them?

It is poorly documented, but datum is an array of key and value, so datum[0] is the key, and datum[1] is the value. This is only documented in Liquid’s old Github Wiki, but not in the official Liquid site. Old Wiki:

Thank you, @chuckhoupt! A while ago I also searched madly how to access key & value when iterating a hash. Forget how I solved it then :).

Thank you so much for your help!!!