code: def clear_unforced_dependencies(self):
      
      self._dependencies_by_address = dict(
        (address, dep) for address, dep in self._dependencies_by_address.items()
        if dep.has_comment()
      )
docs: Remove all dependencies not forced by a comment.
  
      This is useful when existing analysis can infer exactly what the correct dependencies should
      be.  Typical use is to call `clear_unforced_dependencies`, then call `add_dependency` for each
      dependency inferred from analysis.  The resulting dependency set should be the pruned set
      of all dependencies, plus dependencies hand forced by a user comment.