class String

def strip_heredoc

in the whole string, and removes that amount of leading whitespace.
Technically, it looks for the least indented non-empty line

the user would see the usage message aligned against the left margin.

end
USAGE
...
-h This message
Supported options are:

This command does such and such.
puts <<-USAGE.strip_heredoc
if options[:usage]

For example in

Strips indentation in heredocs. 
def strip_heredoc
  gsub(/^#{scan(/^[ \t]*(?=\S)/).min}/, "").tap do |stripped|
    stripped.freeze if frozen?
  end
end