code: def find_module(modpath):
      
      module_path = modpath.replace('.', '/') + '.py'
      init_path = modpath.replace('.', '/') + '/__init__.py'
      for root_path in sys.path:
          path = os.path.join(root_path, module_path)
          if os.path.isfile(path):
              return path
          path = os.path.join(root_path, init_path)
          if os.path.isfile(path):
              return path
docs: Determines whether a module exists with the given modpath.