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The list of paths to look for modules, templated for
module/expand-path. Each element is a two element tuple, containing the
path template and a keyword :source, :native, or :image indicating how
require should load files found at these paths.
A tuple can also contain a third element, specifying a filter that
prevents module/find from searching that path template if the filter
doesn't match the input path. The filter can be a string or a predicate
function, and is often a file extension, including the period.