Feature Request: Add a flag for autofilling default placeholder values

[ajm188]

I like to use sman in conjunction with other tooling, so something like s r my-snippet placeholder1 placeholder2 | awk ....

If I use a default for a placeholder value, but I do not specify a value for that placeholder, it then hangs on waiting for user input (because sman is checking if I want to use the default or override at execution time). It would really great if I could pass a flag to s r to tell it "just use the default for any placeholder I don't override."