code: def p_ident_init_opt(p):
      
      if p[1] == '~':
          p[0] = node.ident("__")
      else:
          p[0] = p[1]
      if len(p) == 2:
          p[0].init = node.ident(name="None")
      else:
          p[0].init = p[3]
docs: ident_init_opt : NEG
                     | ident
                     | ident EQ expr