code: def resolve_dep(self, depname):
          
          for d in self._search_path:
              name = os.path.join(d, depname)
              if self._mock:
                  return name
              if os.path.exists(name):
                  return name
          if self.resolve_dep_from_path(depname):
              # It's a system dep, so skip it
              return None
  
          message = "unable to find %s in %r" % (depname, self._search_path + self._path)
          print(message)
          # The conditional is to ease future debugging
          if True:
              raise RuntimeError(message)
          return None
docs: Locate dep in the search path; if found, return its path.
          If not found in the search path, and the dep is not a system-provided
          dep, raise an error