code: def iter_pyx_files(package_dir, package_name):
      
      for dirpath, dirnames, filenames in walk_skip_hidden(package_dir):
          for fn in filenames:
              if fn.endswith('.pyx'):
                  fullfn = os.path.relpath(os.path.join(dirpath, fn))
                  # Package must match file name
                  extmod = '.'.join([package_name, fn[:-4]])
                  yield (extmod, fullfn)
  
          break
docs: A generator that yields Cython source files (ending in '.pyx') in the
      source packages.
  
      Returns
      -------
      pyxgen : generator
          A generator that yields (extmod, fullfn) where `extmod` is the
          full name of the module that the .pyx file would live in based
          on the source directory structure, and `fullfn` is the path to
          the .pyx file.