[memoir2comment]

snakemake does this trivially:

    rule analyze_country:
        input: 'whatever.{country}.txt'
        output: 'analysis.{country}.txt'
        shell:
            'run-analysis-on-country {input} {output} --country=country'

    rule analyze_target_countries:
        input: ['analysis.usa.txt', 'analysis.canada.txt', 'analysis.mexico.txt']

[elsherbini]

Small change, you have to use wilcards.country inside the shell call:

    rule analyze_country:
        input: 'whatever.{country}.txt'
        output: 'analysis.{country}.txt'
        shell:
            'run-analysis-on-country {input} {output} --country={wildcards.country}'