code: def write_directory(self, directory: str) -> bool:
          
          current_md5_hash = self.get_namespace_hash()
          md5_hash_path = os.path.join(directory, f'{self.module_name}.belns.md5')
  
          if not os.path.exists(md5_hash_path):
              old_md5_hash = None
          else:
              with open(md5_hash_path) as file:
                  old_md5_hash = file.read().strip()
  
          if old_md5_hash == current_md5_hash:
              return False
  
          with open(os.path.join(directory, f'{self.module_name}.belns'), 'w') as file:
              self.write_bel_namespace(file, use_names=False)
  
          with open(md5_hash_path, 'w') as file:
              print(current_md5_hash, file=file)
  
          if self.has_names:
              with open(os.path.join(directory, f'{self.module_name}-names.belns'), 'w') as file:
                  self.write_bel_namespace(file, use_names=True)
  
              with open(os.path.join(directory, f'{self.module_name}.belns.mapping'), 'w') as file:
                  self.write_bel_namespace_mappings(file, desc='writing mapping')
  
          return True
docs: Write a BEL namespace for identifiers, names, name hash, and mappings to the given directory.