code: def write_FORCE_CONSTANTS(force_constants,
                            filename='FORCE_CONSTANTS',
                            p2s_map=None):
      
  
      lines = get_FORCE_CONSTANTS_lines(force_constants, p2s_map=p2s_map)
      with open(filename, 'w') as w:
          w.write("\n".join(lines))
docs: Write force constants in text file format.
  
      Parameters
      ----------
      force_constants: ndarray
          Force constants
          shape=(n_satom,n_satom,3,3) or (n_patom,n_satom,3,3)
          dtype=double
      filename: str
          Filename to be saved
      p2s_map: ndarray
          Primitive atom indices in supercell index system
          dtype=intc