Questions about Linting rules

        Hi, I'm improving and adding more linting rules, but I need
        your comments so thatt things are interpreted right

What is the meaning of sole "f"? Now I issue warning that
h or b or both are missing. Is this correct?

        :0 f

What are the occasions that would would require "w" flag? Right
now anything that has ">" in the action, triggers whining about missing
"w". Is tere somthing else I could check?

        :0                      # Needs w
        | (echo "test" >> logfile)

When the "i" is required? Can I trigger the misuse/required use of
"i" somehow? Suggested rule: if there is no formail call, but there is
"f" then require "i" flag.

        :0 fh               # Needs probably "i" too.
        | big-pipe-to-do-the-job

Is "c" always redundant in "f" receipe?

        :0 fhc                          # c is unnecessary.
        | formail -rt


Does it make sense to have "f" before nested block?
What other flags do not make sense(or are questionable) before block

        :0 fh
        {
           do something

        }